I'm looking at investing in several out-of-state markets (potential BRRRR strategy in mind), I have a list of qualifiers that I'm sussing out to determine viable markets but would love to know: what data helps in determining a good market to invest?

You will need to determine the level you participate in your investment as well it makes a big difference. 

Whether To file a 1065 partnership return or being treat it as a disregarded entity, Is the determination based on the location of the property or the owners' residence state?

Your depreciable basis is determined by your purchase price and expenses, not the seller’s loan balance.

1.Zoning and Land UseUnrestricted Areas & Mobile Homes:How can I determine if a piece of land is in an unrestricted area or suitable for placing a mobile home?

My other SFR notes have interest rates determined by the borrower's cash, credit score and income - so market rates or higher.I understand the difference in performing vs non-performing notes and that performing can become non-performing pretty easily. 

If you determine that the numbers look good, make sure to check other sites to see if the comparable property is on multiple sites that may add to the numbers.  

In the last 18 months various states have instituted new rules, regulations or laws related to (1) need for licensure to wholesale (2) restrictions on marketing of a property in which you do not have ownership and (3) disclosure requirements when dealing with a homeowner that makes it clear to the homeowner that the contact signed with the wholesaler is not a definitive “sales” contract, therefore making it less likely home owners will sign4.

Simply have the tenants sign the new lease AND have them provide you with the additional $100 BEFORE you sign the lease yourself.

You can find qualified buyers that are small business owners, tradesmen, etc just have someone qualified to do prop underwriting be fore you sign the agreement.