Do a walk-through the morning of closing to be sure the tenant is gone and everything is as it should be.If the tenant hasn't vacated, you should do a holdback of enough funds to cure the issue - in this case, an eviction, plus whatever living expenses you incur.The other issue is your rate lock. 

I think you over thinking this in general and not worth it.A  non-curing butyl sealant. 

That being said, if it has had a while to cure, most of the cracking should be done.If you know fighting with the contractor is only going to hurt you more than him, it may be worth having him fill the cracks and be done with him.At that point, you have a couple options as the issue will be more aesthetic than structural:1. paint it.

Supposedly, but in reality, I think not so much.....you would have to be able to force a capable seller of curing something.....title insurance eliminates that need.

How long would you wait for the documentation, or should landlord proceed with 3-day notice to cure or quit?

No treatment, no cure, just a painful death.Cancer is ugly and I guarantee it will affect everyone on the BP forum at some point.

I will assume your tenants are not paying for utilities.What you should do is find out from your buildings department what the allowable number of indivulaes is in regards to the second floor unit and if they are over the code give them notice to cure or quit.

Notice to Comply (or Cure.)

The home inspection contingency is pretty much a blanked escape clause for your due-dilligence, as long as it is combined with NO right to cure for the seller.

Price cures problems.