I live in the house for one year either for free or with reduced living expenses.

It definitely depends on a lot of factors - where non-QM is generally going to be about 0.5%-1% higher in rate, but can be more than that or even lower than conventional with some more options - one in particular is if you did a longer prepayment penalty period (5 years - at a descending penalty structure or even 5% all five years), then that could drive the rate down even significantly lower than the conventional alternative.

I just sold my business and in looking for ways to offset capital gains taxes stumbled across a strategy in which a STR can write off all depreciation in year one via a cost segregation analysis, thereby reducing taxable income greatly for a specific year.

If you’d like, I can pair you up with one of my mortgage brokers and we can help you out.

The reality is if you just do one deal, I suspect you are not likely to be "caught". 

Open question on that one.

In terms of the title, you can go in together and the loan can be under one or both people depending on qualifications.

You find out up front if they have any cash or not, vs burning 30-45 days to find it appraises at your listing price, and they don't have the cash to close.Get a VA checklist from one of your trusted lenders and make sure everything in the house meets the checklist. 

You have to underwrite them as if they didn't have one. 

That is a very tough one to litigate and win, and IMHO it's better to walk and find another buyer.