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

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

You can do a duplex though, which might not be a bad idea.With your credit score, conventional might be a good choice, you only need 5% down for 2-4 units if you live in one. 

@Geovanni Cano sellers don't like FHA, it is meant for people with little money and very low credit score, plus you have an FHA inspection which can derail a deal a week before closing, nothing the buyer can do.

As a US citizen I have an SSN, file taxes every year on my foreign employment income, hold US-domiciled assets (stocks, IRA, 401k), and I have a ~15 year credit history with a decently high score.

In our opinion, Class C tenants have FICO scores from 550 to 600 - where their chance of default/nonpayment is 15-22%.

DIL is a slightly lesser hit than a foreclosure and you wont get a new loan for several years after. 

Interesting approach, how would multiple refi affect my credit score?

: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+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, 1-3 years for positive cashflow, 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 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, immediate cashflow and at the lower end of relative rent & value appreciation.

On the flip side, if you've got a bunch of Section 8 tenants living in a building that's in a neighborhood where a lot of the tenant base has good jobs, high credit scores, and are generally reliable people, you've got the most risky tenants in that tenant base and that ain't what ya want.