They help prevent after-sale tenant disputes or surprises about matters that originated with the former owner.

I really like OKC but it has tornados that kind of prevent me from looking further. 

Unfortunately due to the business you choose to operate incidents like the one you experienced are more likely to occur compared to a property that's continually occupied by a tenant where the water would more likely be run at a higher frequency which would prevent the pipes from freezing.  

In other words, I already have a checking and savings with BoA, but I would create a 2nd savings account (within my regular account) and put all the rental properties last months and security into that account (combined).Is this the correct way to prevent co-mingling of funds, or what would you recommend?

Don't let "analysis-paralysis" prevent you from your next great deal(s)!

That, and escalation clause prevents you from just blindly offering your best offer out of the gate. 

If you do end up segregating, keep good records to prevent having to recapture the depreciation of the reclassified assets.

Do any of the tenants have Dogs (Breed restrictions are individual to each company).These may not prevent you from getting insurance but they may limit the number of companies willing to insure it.

I told him to pull out everything that might have gotten wet, get everything dry (to prevent mold), and make sure it was done right. 

That could possibly be preventing traffic.