However, understanding their requirements—such as down payment percentages, reserve requirements, and loan-to-value ratios—is key to getting approved.One of the biggest advantages of working with portfolio lenders is their ability to fund deals that traditional banks might pass on.

Not sure when you purchased the property, but keep in mind conventional loans require 12 months of seasoning before you can use the appraised value for a cash out refi.

Stessa is a great option, but Baselane is my current personal favorite, partly because it doesn't require that you use a special bank account for rent collection like Stessa does. 

It's the one-year required management agreement at 10% that can get you (although you can re-up the following year at a discount if you pay the entire year at once).What you definitely need to avoid is leasing through them, should your property become vacant.

It means that your 2nd required stay can straddle the new year, and it still counts!

Hello,One of my single family rentals that is outside of Atlanta, was heavily damage in a fire and most likely would require a full rebuild. 

These are boiler plate loan agreements that are consistent with the loans underwriting requirements.

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

I would read up on the requirements of an S Corp.

Please be aware that all national homebuilders, and I would assume solar developers as well, will want enough time in the contract to conduct substantial due diligence, rezone (if needed), and get all required land development permits in place before closing on the land.