I've spotted some trends in the STR market and am eager for some insights.It appears there's a surge in new listings, causing occupancy rates to dip even as booked nights go up.

If the appearance of being in an LLC prevents one law suit it is well worth the cost but it may not ever prevent a law suit. 

Well, it appears that Tik Tok is going away, so that's good. 

If it were an exclusive buyers agreement and insisted on 3% with no contingencies, that is a lot more rare and broker-sided but from the terms you've provided, it appears he's just trying to protect himself from timewasters.

Ask your accountant to read Regs 1.469 and CCA Memo 202151005.You can have Nonpassive Schedule Es under certain circumstances but it appears he is listing it as passive, therefore creating suspended losses.Here is a previous thread: https://www.biggerpockets.com/forums/530/topics/1056436-clearing-up-confusion-on-tax-treatment-of-short-term-rentals

These entities do not appear to be set up as self-sustaining independent businesses. 

Your cellar appears to have potential based on its features like full-size windows and a separate entrance.You're on the right track!

Are you around the equivalent of 1.5-2x LTR  and 1/2 of STR?

So, would you rather figure this out on the fly what appears to be a one-off transaction? 

These appear to usually be bundled with security deposit replacement coverage.As for surviving the pandemic, MANY didn't.