Damros is not in the mood for banter and bartering.  He will put down one gold and one silver on the counter for two writing sticks and at least 6 sheets of decent paper.  Once presented he will roll up the paper and slide it into his shirt and grasp the sticks like a dagger as he swiftly returns to his companions.

Damros shoves a paper and a writing stick out to the group like it is covered in sewer rat droppings... "How about one of you smooth talkers write to Mirt and just tell him to meet US back at our 'home'?   I saw a shop down the way where we might be able to sell these stealthy boots... maybe it could cover the cost of dinner tonight?"

"Just slip it under his door so nobody else reads it of rips it off the door?"

Skye takes the paper. ‘We know you’re here. Nice place, come to the inn, or else there’ll be no happy outcome here. Be seeing you.’ A nice, normal note. She makes her mark at the end. 

You mark the note and leave it, checking out selling the boots on the way back. Upon inspection, and seeing the fine drow craftmanship, as well as the intrinsic magical properties, you are offered 1200 dragons for it. Or alternatively if you are interested in exchanging them, they are willing to provide some Winged Boots with no exchange of money in either direction.

With the party seeming set on what to do with the boots, Xaul will sell them for the 1200 dragons offered once he's given a definite go-ahead.

Skye gives her nod in a vote of approval. 

"Who knew selling a pair of boots would allow for a week of work and repair for the tavern.  I must take better care of my own footwear,"  Damros smiles as they all make their way back to the tavern.

I will assume you make the necessary payments and instructions to start the renovations and then the guild joining. We will not RP it all but there will be a few moments during the process that I will bring in.

You head back to the tavern richer (and possibly depending on when you go to start the renovations, also poorer in physical money, but richer in assets) and wait to hear back from Mirt. You are all sat there discussing your plans with the place when you hear the cellar open by itself again. This time looking over you see four tankards floating by themselves from the storeroom, making their way to the bar where they are filled with whatever drink is still safe for consumption over there (yes, you will get new alcohol deliveries as part of the guild fees) and it is then carried to your table.

“I didn’t do that,” says Skye, after a moment. “Did any of you do that?”

Xaul looks up as Skye speaks, his arm midway outstretched towards the floating tankard ready to take it without a thought. His eyes move from her, to the mug, and then back again, before he slowly retracts his arm and says '...No, that wasn't me either. Should we, uhh, investigate? Seems this is yet another visit from whatever was causing that racket before, but it seems to be a little friendlier this time...Perhaps it's changed its tune now we've decided to fix up the place?' He leans back in the chair and hesitantly calls out 'Thanks for the drinks, whatever you are, but we'd really appreciate if you show yourself, if you can. If you can't be visible for whatever reason, maybe give us a sign that you can hear us and you're friendly, like, I don't know, knock over Damros' ale!' He smirks at the Shadar-Kai from across the table, and waits to see if there's any sign of the unseen creature.

The ale in front of Damros falls over. And then gets picked up, and carried back to be refilled. And as it is brought over, a cloth is brought with it to mop the spillage up.

Sehaethas asks Kylaski, "Do you know what this is?"

Arcana 9, Religion 13 I'm guessing Kylaski doesn't know either.

To the spirit, ghost, or whatever it is, Sehaethas asks, "Would you want to work at this tavern once we fix it up? Lift my drink for yes, slide it to the side for no."

The drink lifts up 

Skye takes a sip of the beverage. It’s hoppy but … refreshing. It’s cooler than she prefers, but in the muggy waterdeep air it’s … deeply thirsty quenching. 

“We’d be glad to have you. Do you need payment, or convocation? What tithe is your service worth?” She haggles. 

Damros grumbles as he dabs at the spill in front of him. "I suppose this explains how I got locked in the cellar before.  And, perhaps how that water puddle turned into ice shards that flew at me."   

Sitting upright, he addresses the air in the room,  "I do not know what I may have done to be the target of your ire.  I apologize for any offense I may have given.   I too ask along with Skye - what accommodation can be made with you?"

Sehaethas changes into Kylaski, who then says, "We should call our tavern the haunted tavern! Not many taverns have a ghost for a bartender!" She then asks the spirit, "Do you like that name?"

Xaul grins as the party and the spirit introduce themselves to each other, and turns his seat around and scratches his chin as Kylaski raises the idea of having the ghost be part of the tavern's marketing. He thinks for a couple seconds, before saying 'Well, I wouldn't quite put it as on the nose as The Haunted Tavern, might scare some folk off, but that's a very good idea nonetheless! How about we go for something that's a little more subtle, but still nods to both us and our spooky friend? How about The Pact and Phantom?' 

“Poltergeist,” says Skye. “The Pact and Poltergeist.”

You notice that following saying it would work here, the unseen force hasn't answered any question. It seems you might need a better way to communicate  when the questions aren't as straight forward yes or no ones. (which is a shame that awakened mind requires seeing the creature) 

Kylaski agrees, "Oh! I like the Pact and the Poltergeist!"