Caszimir similarly leaves his coins, notably using the same dragon he was just tossed. Regardless of how things went, one could argue he got his discount anyway. 

...however, with the shopkeep possibly distracted with his coin counting, Casz can't help but swipe something as he leaves, though he doesn't actually check what. He counts on luck that something doesn't happen.

[Sleight of Hand: 17]

He manages to swipe a tiny purple chest carved to look like it has numerous feet on the bottom. You don't think you were noticed.

„What a place,” rumbles Oriace and rolls his eyes when finally everyone left the shop. “Let’s go to the Skewered Dragon,” he says and turns to go.

You follow the directions and reach your destination. The Skewered Dragon looks like a ruin. Both of its front-facing windows are smashed, and a ship’s anchor is lodged in the roof. Through the windows, you can see a group of haggard patrons drinking from huge tankards.

Wagner pauses, "What's our play here? Just looking for a good time and play it by ear or direct questioning?"

Casz fixes his hair in the shattered remains of one of the front windows and undoes his top button. 

"'Don't know about you boys, but I say butter 'em up first. I admit, I'm not thrilled to have that crowd staring me down, for whatever reason, but it's less likely to cause a scene than if we just went into it straight to the point."

He thinks about it for another moment.

"Or... how about we split up? Two of us draw the crowd, two more asks the questions and whoever's left disguise themselves as a patron and listen to the crowd for rumors."

Sterling nodded. "That works for me; I'm all for the get-right-to-the-point approach.

"If someone else joins me, we can go in after everyone else. We wouldn't need to bother hiding or being anything other than direct; we might even be able to offer a reward for any info if the patrons seem... amenable."

Speaking in slightly slurred words, Curtain explains his idea: "See man, a bartender always knows anything worth knowing. They be hearing stuff." Then in a slightly intimidating voice, he continues: "Let me talk to 'em." In contrast to his voice, he happily nods along to his words.

"I wouldn't mind sitting back and playing a few beats on my drums if someone else wants to perform something," Oriace adds. "I need to calm myself after that encounter with that sorry excuse of a salesman."

Wagner hates taking the lead but we need action. "I don't feel like we're any closer to having an actual plan. I'm saying we go with the split approach. Casz, you go in first, you're pretty good at listening, blend in and pay attention. Curtain and Oriace, you go second, and work the crowd get them in a good mood. I'm pretty good at sussing out lies, so Sterling and I will take up the rear and ask the questions. Any objections?"

So, based on this plan, I believe I need Oriace to make a DC12 performance check (and possibly Curtain if he is also working the crowd, or one of you with advantage). I then need Wagner and/or Sterling to make a persuasion check, with advantage if the performance check passes, to try and get the patrons to talk. (equally can be intimidation if preferred).  Casz I need a performance check (flirting) or slight of hand check (pickpocketing) from you depending on what you are trying accomplish here. (Other options available but that was what I assume based on character history)

If anyone offers a bribe of.. enough... , then I don't need any checks for getting information, but you can still do rolls for anything else you might want in addition. (I did write how much is enough but don't want that to influence you. I will let you know if it is enough if it gets offered)

With his head tilted to the side, Curtain blinks a couple times while staring at Wagner. He than shrugs and starts clearing his throat, telling Oriace the name of a rowdy sailor song to play. He gives Casz a minute to get lost in the crowd, and then pushes in through the door upbeatly singing: "What will we do with a drunken sailor?"

Performance: 14 

Oriace enters just after Curtain. He'd known the song but even if he hadn't, he would just improvise. Working his drums, his thought returns to that the little box that sounded like breaking waves on the beach. Pity that the old gnome didn't budge. He joins in with Curtain to rouse the crowd, "... Early in the morning!" 

[(Takes loooong sip of coffee; "goddammit.")OoC: Caszimir is still Caszimir, so regardless... Performance: 15]

The Eladrin strolls through the door with his usual swagger. Though the prospect of being... near this element throws him slightly off his game, he nonetheless follows through with his typical candor. He strides over to a particularly populated section, sitting gingerly on a wobbling chair, and leans on the table with his legs crossed. Removing his gloves, he rolls up his sleeves and flashes the crowd his trademark smile; he speaks with a wistful sigh: "Well, now. Could I trouble someone for a drink...?"

'The bait is set and the line is cast. Let's start fishing...!'

Sterling waited a moment after Caszimir, then nodded to Wagner and headed into the tavern. He wasn't liking the decrepit place, and wanted to get this over with as quickly as possible--so he took a few seconds to look around the place, then made a beeline right towards the barkeeper.

"Look," he said in a low voice as he quickly found a seat and leaned in. "We don't want any trouble, and we're not here to play games or waste time. We have a friend of ours, Floon Blagmaar, who's gone missing, and we just want to find him. If you've seen him, or know ANYTHING, we'll be more than happy to compensate you for the assistance." He slid a couple of gold coins towards the bartender under his hand as he gave a brief description of their quarry. "And," he finally added, tapping a finger on the bar, "this would be the down payment of your compensation. Assuming you can help."

The bard kept a steady gaze on the man, searching his eyes for the slightest hint of fear, recognition, or worst of all, lying.

(( Persuasion Check: 22, 2nd roll for advantage if the Performance Check passed: 23
Also, an Insight Check if needed: 22 ))

Wagner follows Sterling in, staying close and trying to keep an eye for reactions. Insight 18

The barkeeper starts to respond, and then several of the regulars also chip in. Despite being quiet, it seems everyone started to listen in once you started being hushed. The barkeeper and a few of the regulars remember seeing Volo and Floon drinking together a couple of nights ago. After Volo left, Floon stuck around long enough to meet with another friend: Renaer Neverember, the son of Waterdeep’s previous Open Lord, Dagult Neverember. “Chip off the old block, that one!” sneers one patron. “Just another spoiled, rich noble who likes to rub our noses in it!” says another.

The two drank and played a few rounds of Three-Dragon Ante before leaving around midnight. Five men followed them out, and no one in the tavern knows what happened after that. The men who left shortly after Floon and Renaer haven’t returned to the tavern since, but they’re known to frequent a warehouse on Candle Lane. “Look for the snake symbol on the door,” says the barkeeper.

No one seems to be lying. They are in good enough spirits, especially the barkeeper for that tip. He even pours you a drink on top of the information, in a mug that is mostly clean.

Casz: You get two offers to buy you a drink. One from a male Illuskan sailor who looks half drunk himself already, and the other from a female gnome, who was previously sat on the lap of a now rather put out dragonborn.  

I do love this part of it, at least, he thinks. 

He even beckons the Dragonborn, putting all his charm to use. [Performance to net that extra patron(?): 24] A smile here, a caress of the hair there, a wink here, a sweet little chortle there; oh, how they're putty in his hands. All the while he plays the curious listener, as the others make nice with the barkeep and his coin purse. Occasionally, he asks a real question, passing it off as "innocent" curiosity: "What did they talk about, I wonder? The Lord's son and that man." "Do you think the guards know those men, what followed them?" "Gracious, but what d'you think happens at that warehouse?" [An added Persuasion check, in case any of them need that extra "push": 21]

He'll take the rumors and the testimony. Sometimes, folks are far closer than they think... well, mostly. He's fairly certain the world isn't run by a horde of faceless men around a game board, deciding fate with a die and the like. That's just ridiculous! ...And in any case, the gnome's company is pleasant enough. The sailor's far too handsy and can go suck an egg. 

Yet even with minor disdain, he plays his part to all three (or two, if the Dragonborn isn't hooked). At the end of the day, he's still a shameless flirt, but with free drinks to boot!

DM: Have I seen or heard any groups associated with a snake symbol?

Depending on if the others want to leave as soon as they have their information, or if they wait around for a bit, Casz is able to get up to 4 free drinks in total, with the three of them eating out of his hand. The only (as well as anything mentioned generally above) information comes in reply to the second "real" question, from the gnome "Pretty sure those men might be known to the guards. They watch that warehouse too" they lean closer to Casz and whisper in his ear "Tis the symbol of the Zhentarim" before giving his ear a quick seductive nibble.

@Wagner, possibly. If your character has any ties to the Zhentarim (can't remember backstories off the top of my head but I don't remember any), they would, otherwise make a DC15 intelligence check. On a success you know they have a winged snake as their symbol, which put together with the fact they were involved in the fight earlier, would be enough to put 2 and 2 together. DC10 is enough to know of their symbol being a winged snake (so when you see it at the warehouse you would know. As that is a check given in the module), but a higher DC for knowing without seeing it, and without wings mentioned.