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

It's not like comparing apples to apples where you can view one 4 unit building against another unless you are building identically permitted buildings on parcels that share the same site conditions.

I have verified with local management company the availability of tenants.

The seller doesn't have the borrower's driver license or any identity verification paperwork.

If the mentor knows what he’s talking about, has the experience and a verifiable track record then it could be a very cost efficient way of obtaining one on one guidance.  

Seller won't release any further info until Buyer is verified, POF etc..

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

The cost of all the vendors to process a loan: credit, audit, LOS, tax, Underwriting, processing, verifying every piece of paper is a range of $9000- $11000 per loan. 

If you have no US credit, lenders will want to verify to credit trade lines from your country of origin for the past 2 years.

They are likely representing the identical insurers.