Hi Doug, my wife and I are looking to get into this type of business for displaced family's.

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

As you look to scale your portfolio, first, ensure your mortgage terms allow for flexibility, such as the ability to refinance or access equity.

Or is that not allowed, depending on the state or lender?

This is exacerbated since J taxes allowed, until a coupld of years ago, accelerated depreciation on foreign real estate.  

LY 90% of our business was with out of state investors, and about half of that was in STRs.

I didn’t acquire my portfolio by being some sort of an investment genius, rather, I just used profits from my business to buy whenever I had an opportunity.

Slightly off topic..NEVER allow smokers as tenants.

You need a massive marketing budget, and you need to double close on the property, meaning you need the actually have the cash to buy the place.Flipping contracts from unknowing sellers to buyers is a shady business, illegal in most states, and has a failure rate in the high 90% range. 

Any business experience, contractor skills, etc.