So if I were in your shoes I would want to be really confident in the exit strategy. 1) confirm rent estimates 2) confirm ARV and the demand in that area to buy a house like that in the price range 3) are there banks willing to refinance at the LTV you want with the seasoning period you have. 40k for a house of that size that needs that work would be the cost of materials alone where we live in WI, so verify your estimates.

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

Do you verify their income?

I have verified with USPS that each triplex address is in their database and that there are no issues with the location and height that I would install it at.

How can I verify this in the future when there is no power to the home? 

If Jesus came back and got into rentals NO, N-O-B-O-D-Y get's admin access into our system. 2) They want a standardized list for maintenance items so they know in advance what repairs would cost.Being a PMc I'd invite them to acquire any of the readily available construction estimating tools/software out there such as RSMeans, but would not take on such a task as building and maintaining such a database, honestly for any $, it's simply not what we do. 3) They want a copy of all invoices from contractors to us so they can verify we are not marking up more than promised.A-ok. 4) They want to be able to talk to our contractors before work is done (each time) so they can talk contractors down in price themselves.I'd be fine with this as long as they sign a waiver that they own any/all negative impacts that result from such including extended vacancy periods, vendor refusals of service necessitating there own self-search to secure amicable vendor etc etc.. 5) They mentioned that they pay around $300 for full paint in a 2-bedroom unit.... we do not have a contractor that will touch a full paint on a 2 bedroom for $300LMAO!

The best way to verify that is call the current agent for the policy and ask them what happens when you buy it - will the carrier still offer a policy?

Or verified everything with a realtor or even ordering an appraisal 

He claims they are verifiable online and that I should be comfortable doing business over the phone and internet.

In a 506(b) deal you are allowed to bring in up to 35 sophisticated investors that don't meet the accredited standard, and almost as many as you want accredited investors.  506(c) you can market offering, and need to take reasonable steps to verify they are indeed accredited.Reg A(+) you can market and raise from non-accredited, but more regulatory filings.I think there are a lot more accredited investors than you think.