Are there other tax structures that are possible or that you would recommend if we did not go with the TIC? 

(I'm patient and will need an extension anyway due to my K-1s) I have been trying to find a new CPA for my 2021 taxes and so far the only ones who have real estate specialties that I have been able to get a hold of are those who assist active investors who structure the deals as a GP or RE investing is their main source of income.

Probably the biggest changes will be if the states have different legal structure for spouses, such as tenant in common, etc., and how those are handled when selling a property, as well as the agent responsibility if it is a non-disclosure state vs not.

Things I learned in my first job that have continued to prove valuable today: underwriting, managerial accounting, private equity deal structures, what a side letter is, what investors want out of deals, what a K-1 is, why real estate is a valuable investment class, what asset allocation is, where to find tenants, what cam is, how to handle Capex items in sophisticated underwritings, loan docs and negotiating terms thereof, understanding a lease, what an estoppel is, what a phase one and phase two are, how to read a PCA, basics of land use and zoning...Oh and best of all, I got paid to learn all of this stuff.  

Rental in FL has equity of $280k (mortgage of $200k) We would also like to structure as a business or trust as opposed to reporting everything on our personal income.

Just trying to see how I would structure that question.

Family member wants to sell a property no longer needed and put all of it into our STR ($600k).I'm not sure how to structure the calculations on what a fair split would be after my family member deposits the extra $600k towards the mortgage.

Given what I know it needs without even seeing it, though (new roof, fascia repairs, animal control, new boilers, lead and asbestos remediation, oil tank removal--and that's without knowing anything about it structurally or cosmetically on the inside), I'm guessing I would have to put in roughly $100k in rehab.

Case in point the area where I live has many houses downtown built on cedar post foundations, which are at end of life, and its a hot market, so what it appears is many investors just do nothing with the foundation if the house is within a couple inches of level even though the posts are rotten and will cause structural issues a few years down the road. 

If it is the unpermitted issue, then you have to determine if the permits can be issued retroactively and if so how much risk you have that you will need to rebuild some portion of the structure.