what is the best way to fund renovations on a flip project (other than cash)hard money lender, line of credits, credit cards?

If you have access to a line of credit on your primary home, that could be a good option.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

The prospect completed an application and checks the credit and income boxes but does have a mark on the criminal record.

Since you're in Florida and the laws are much more fair, I'd be willing to take a chance if his background/credit check came in clean. 

The home buying process typically follows these key steps:Assess Your Finances: Review your credit score, savings, and determine how much you can afford for a down payment and monthly mortgage payments.Get Pre-Approved for a Loan: Work with a lender to get pre-approved, which gives you a clear budget and shows sellers you’re a serious buyer.Find a Real Estate Agent: Partner with an experienced agent who knows the local market and can guide you through the process.Search for Homes: Browse listings and visit properties that fit your criteria (location, size, price, etc.).Make an Offer: When you find a home you like, submit an offer through your agent, including contingencies (financing, inspections, etc.).Home Inspection & Appraisal: Once the offer is accepted, hire an inspector to ensure the home’s condition and the lender will order an appraisal to verify the property’s value.Secure Financing: Finalize your mortgage by submitting required documents and ensuring the lender clears you for closing.Closing: Sign the final paperwork, pay closing costs, and receive the keys to your new home!

You've already gone above and beyond, but it seems you just dig up more problems.When you run a credit/criminal background, the credit report should list the applicant's current and previous addresses.

I'm moderately experienced in subject-to (had approx 6 over last 9 years), but this will be my first time as a seller with the underlying loans in my name and more of the risk on my credit.

I think you are definitely on the exact right track with your thinking - have you put all this side by side in excel (very basic excel "modeled out")>? 

My credit score is 700+ so I don't understand.