I have enough to put 20-30% as a down payment with ~800 credit score.

If no U.S. credit score, a lender will assign a mid range one-I've seen programs assign a 680.

DSCR loans are most impacted by the property's cash flow and your credit score. - Derek Brickley brought up a great point about Seasoning requirements.

:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+, zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680, some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

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

They have been incredible in dealing with my properties across the country and I'm looking to bring some value to them.  

@Marcus Auerbachinteresting post.i really don't know.as @Cody Roberts pointed out, another thing that is happening at the same time is an incredible reversal of population growth - from the doom and gloom, overpopulation predictions of the 60s and 70s, to the likely peak of human population by 2060 or 2080, followed by probably an irreversible decline. 

People pay rent with money, not their SAT scores. 

Primarily this applies to when one took bonus depreciation on land improvements, or in the case of nonresidential property, qualified improvement property.The one type of depreciation recapture you can defer with an installment sale is "1250 unrecapture" - this is that typical 25% depreciation recapture rate that you think of, which is the depreciation recapture on the straight line building and/or straight line depreciation on something like the previously mentioned land improvements or qualified improvement property.Allocation of the sales price is incredibly important here. 

I’ve always been a money-knowledgeable young man; credit (760 score), stocks, roth ira, 401k, etc.