They run your credit report to start so I did not love that.  

Not sure how best to do it, but a larger first time homebuyer credit makes no sense to me. 

What is the lowest up front amount we could get away with? 

If tenants are moving out right after closing, do double check the leases clearly show the security deposit they paid the seller and you collect that amount at closing from the seller (credit to you) so you have those funds to then return to the tenants when they vacant under your ownership. 

Then another thing I see coming down the pike is the credit card debt.

What kind of credit score do they have, and is it high enough to meet the requirements of lenders?

Spring appraisals use winter comps, which often creates an issue when you sell a property in the highest price season and use comps from the lowest price season.Refi appraisals are generally the worst.

The loan can be called, but in the 45 years I have been doing this I can only recall a handful of cases and it usually was Credit Unions or private money lenders.  

Any landlord that thinks a tenant owes him something can file a collection and mess up their credit?

Also no one with felonies, evictions, or credit under 650.