Let them know you will inspect to verify.4.

Like I said, verify the disability first!

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

You can choose to terminate their leases and start fresh, or verify their ability to pay the new rate.

If you are trying to buy a bank owned property you just send them the contract they want you to sign and proof of funds, or if you have financing, the commitment from the financier, who may also have to provide their own verifiable proof of funds. 

If you total monthly rent is $1,000 (you should verify) with a property value of $145,000 may not work in order to cash flow.

I wonder if you got in touch with Amex and verified everything beforehand and had them reach out to closing attorney if that would matter.

Make sure you're performing credit checks, background checks, verifying income (calling employers and even checking bank statement if you need to), and calling former landlords to inquire about/confirm their habits as a tenant (cleanliness, respect for neighbors, paying rent on time, etc.).If you don't think you're capable of this, definitely find a good property manager!

The additional person also increases the chances they have funds in a bank account that can be seized, as well as other assets that can be seized (verify bank vacuuming is allowed in NY). 

Assuming I had the experience, I would only buy a place with structural issues if I had 1) an experienced and trusted structural engineer telling me a clear, and verifiable explanation of the cause(s) of the problem and a viable and affordable solution, 2) trusted and experienced tradespeople who would be implementing the solution (carpenter, mason, etc.) confirming with me that they could fix the issue (with 90% or higher confidence that the issue could be resolved within budget), and 3) confirmation from city inspectors that the issue (and an inability to fix the issue) would not result in condemnation/revocation of occupancy permits. ...and even then, I'd only proceed if I had the cash reserves to ride out a major series of unexpected problems (e.g.; time overruns, budget overruns, unexpected revocation of occupancy permits from the city, etc.)