When title transfers, the lender has the right to require that the loan be paid off entirely.

From what I quickly read in the link above, seems like you just need to have a bank account that is govt insured and earning interest, doesnt have to have the tenants name on it, but you need to inform the tenant of account and rate the account is receiving. 

So if they pay more it is not that they pay over market rate.

So the point of this is that what often occurs is that in the year that you close on your purchase you start out at the seller's old property tax rate.  

I’m sure audit rate on this has to be astronomical and just need good records?  

They mentioned that the rate will be higher if locked for 5-6 months.

It requires the borrower has significant experience and is very costly (in terms of rates/origination)It's generally really risky to do 100% financing especially if you are inexperienced.

The challenges include - Interest rates - that are as high as they have been in 20 years; property values - which have doubled and tripled in the past 3-5 years.  

-will I be able to keep my interest rates?

Cap rates are pretty useless.