With an STR, it has to be absolutely clean, a guest does not want to find evidence of prior guests at all. 

I will research my market to find out what's required for my state.

Provide a detailed accounting of deductions, along with the invoices, to show you’re acting in good faith.

One major things to consider that many newer investors miss with 5+ units, is that if you intend to hold, the property will need to be at least 75% occupied and stabilized before you will be able to find reasonable financing terms. 

Every conversation you have, find ways to bring real estate into it.

Talk to a trusted lender (preferably local) about what loan options are available to you.You can absolutely find some solid SFRs or even multi families around, but the cash flow on many will be lower the first few years, unless you are willing to do some value add work or buy in distressed areas with less expectation for future appreciation or price stability.If the goal is to have value down the road to cash in for a pivot, don't forsake appreciation for maximum cash flow.

If they don't have any...then we need to find one that does.3.

It's not illegal provided you're dislosing it to all parties and not trying to actively hid it.

We are a small partnership with 4-5 properties currently, but we are growing and hoping to find a reliable lending partner that we can do repeat business with.About 3 months ago, we successfully completed a BRRRR deal where we had excellent numbers, over a 1.25 ratio at 75% LTV, our guarantor partner has an 800+ credit score, and we had no issues qualifying for the loan.

@Micki Ray Harper  In a quiet title lawsuit, you are obligated try to find people who should be defendants.