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

He is probably drawing up a Quit Claim Deed, which is usually a 1-page document.  95% of what is in a Quit Claim is copy / paste so it shouldn't take that long. 

If so, did you use an attorney to do it or were you able to draw up the documents yourself and have them recorded?

@Moira BaggettWithout knowing what “failing” means - there is great advice from others on this page.One thing I would do is go back and read your documents to see what happens in the situation you are in.

Go to Etsy and search for "rental property tracker," and you will find hundreds of nice spreadsheets to track 10-20 rentals, usually for under $10.Software has extremely helpful features like online payments, marketing syndication (click a button, and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.

Thank you -  Any other documents I should look into? 

I would also try to familiarize yourself with local landlord-tenant laws, including fair housing regulations, security deposit limits, and notice requirements for entering the property or terminating a lease.Prior to renting, conduct a thorough inspection of the property before the tenant moves in, and document the condition with photos or a video walkthrough.

If Subs pulled permits, and they are not complete, you will need the contact info for the subs used.5- Perform a photo documented site inspection, written detail of unfinished work directly covered by the language/scope of work description in your contract. 6- If permits are complete, signed of as FINAL, no further inspections required, then solicit an estimate from another contractor for the list of unfinished work.

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

I am dealing with this situation with a client of mine where proving those payments is hanging up the refinance, so as long as it is clearly documented with the exact lease amount being paid over that time in the account, then most groups should be fine.