We use Myrental.com to do all our background checks and collect ID and pay stubs from there.

They're not going to close the deal without the money for current taxes due being collected, so you don't have to worry about it.

Worse, they could put the collection on both of your credit reports, which could show for 7 years even if paid.  

They would not do anything and just collect the check for the sale.

If the state has held a Certificate of Sale less than three years from the date of sale by the county tax collection official, the Certificate will be assigned to the purchaser.

Unless she's breaking some rules, don't do anything but collect monthly rent. 

The work is pretty extensive so I want tenant to move out temporarily while the contractor can do the job easier.

Along with an expectation that your questions are reasonably infrequent and do not require extensive research.It's somewhat like a buffet.

Any best practices on collecting past due amounts?

Since I am not really changing the main purpose of the property, one source told me it shouldn't apply.Lastly, do make sure you apply for an account to pay your sales (collected by Airbnb and vrbo, but not others) and Tourist Development taxes (you must collect).