Most competitive lenders will want to verify the above.

And is there any way to verify it has actually been done properly if and when we get there?

One of the major differences is making sure you are not transacting with disqualified persons, but the documentation can be much the same (or identical) in most cases.

Verify breed and specific dog.

Sounds like your experience is almost identical to mine.  

I guess I am wondering what else I can do to verify that the lending firm is solid? 

Verifying last 2 years of rental history very important!

These properties which are almost identical to my property are valued at $100k or more less than my property.

If the successful bidder assigns his interest in any real property purchased at the Delinquent Tax Sale before the end of the redemption period, the grantee from the successful bidder shall furnish the Tax Collector with a conveyance, witnessed and notarized, a copy of the bid assignment form may be obtained from the Tax Collector's Office.Bidder checks (for the bid amount plus interest) will be mailed to the successful bidder, or their grantee, once a property has been redeemed and funds have been verified by the Tax Collector and pay periods have been determined.

So, while a lender might have you approved for “conventional” financing when you get prequalified just verify with them that they are qualifying you with Fannie Mae specifically to get this benefit.Happy hunting!