B NOW HAS THE MONEY C HAS LENDED, B THEN TRANSFERS ALL THEIR LEGAL OWNERSHIP OVER TO C WHICH COMPLETES THE LOAN AND EXECUTES THE B&C CONTRACT.  

Yes, things like job transfers or your family growing are absolutely justifiable to move...and if you did move they aren't going to come after you or anything....but we don't want to commit mortgage fraud. 

Is it possible or we can only get qualified for it when we get transferred?

He says this description makes it sound like the Assessor's Map is used as a description which is illegal and won't transfer ownership.

Looks like you get to make some invoices, and or attach the transfers into their bank accounts.

In our case, we had the intent, purchased the home, moved in, and a few months later, I got transferred (active military). 

In regards to your concerns about a bank exercising the Due on Sale Clause, you can check out this article on Land Trusts which explain an exempted transfer from lenders. 

Ask the seller to reach out to the tenants and let them know the building has sold and the current leases will be honored and deposits transferred to you. 

The biggest hurdle is obviously the transfer tax that I will have to pay based on the assessed value.

You will need to have an inspection as part of the transfer process.