The original lease would still stand, but you can have them sign an Addendum just to acknowledge the switch of ownership of the lease ( you) and where payments are to be sent and how they are to be made out, or if online payments, how to pay. you can not physically change the rent and i wouldn't bother re writing it on your co. letterhead, that would be a waste of time and a headache.

I've read through the contract particulars more tightly since my post - and found another area that addresses it immediately: "In the event Buyer and/or Seller choose not to purchase a HWPP prior to recording, this paragraph shall serve as acknowledgement Buyer and/or Seller wish to waive their right to purchase the plan."

The lease just says that the landlord has to give 24 hours notice, but does this mean that the tenant has to acknowledge receipt of the notice? 

Great place for cash flow if you're willing to acknowledge that you may be unable to exit the investment for any premium. 

I would make sure it's written in the contract that the seller acknowledges you'll be recording the memorandum to give notice of the existence of said contract.

yet took some rather odd actions.For example:Board started digging drains in front to of my house without ever acknowledging my engineer's letter about the damp, or coming in to look at where it was coming in.This was not recommended by the engineer.Meanwhile, I was waiting for funds to replace the carpets and while delays went on I had to move out the house because of the risk of mold. 

It's a risk, but it's an explicit, calculated risk with which you have acknowledged you're comfortable.

Acknowledge that he's not a tax strategist and advise me when to consult one.  

If the first date [21 days after tenant vacated] always resulted in accelerated "expiration", then the language in the paragraph would not make sense.I acknowledge your answer, but I would appreciate if you could corroborate your interpretation with an example (with or without early termination) where the 60 day rule would come into effect using an alternate definition of "expiration", or with case law.

Just ask them to acknowledge they received it.