potential posters on a job board for a oneshot that has small ties into the regular homebrew campaign? and also npcs?

HI! new-ish GM here. 

i'm running a homebrew involving a short, in-between-real-session adventure, and i need a few more ideas for poster options for the players to follow! its lighthearted and funny, but can absolutely be concerning at times. 

so far, i have a wizards shopping list posed as a serious quest, a lost kitty poster in crappy writing,  and a hitmen wanted poster with not-so-subtle references to Supernatural. they get to talk to sam and dean. (dont ask me the timeline, i have no clue when this is set...)

anyways! do yall have any ideas?

i.. also really need NPCs for them to interact with. i am so, so bad at character creation. please. i need help.

The best advice I can give you: Do not use a quest board for a one-shot.  That is just asking for you to do a whole bunch of prep work on content that you will not be getting to - after all, you will have to prep every possible item they might choose from a quest board, even ones you might not get to.

Instead of focusing on a series of different items, the best one shots focus on a tight, self-contained plot that can be finished in a single session.  Any one of your ideas could be the basis of that.  I would recommending choosing the one you resonate with most and expanding that concept. 

I think this can roughly work if you use the adventure modules like Phandelver, Keys from the Golden Vault, Candlekeep, basically the anthologies, and using the adventures of the proper level and powers as the options. Ofc the hardest part with this then is making them all fit and work with another thematically and story wise (like Infinite Staircase or Candlekeep).

On the NPC creation, a good way to quickly create NPCs is just to assign them one personality trait. "Cheery", "Haughty", etc. That's plenty to go off of for a quick interaction. For a major NPC, you can give them a second trait that doesn't seem to fit with the first. Then think about why these traits do actually go together for this individual.