With that said, you technically can refinance any time you want after you close because these conforming loans generally have no prepayment penalty.The other aside that I will mention is that you will want to make sure you have sufficient comparable sales in your area that will be able to document enough value before you spend money on a non refundable appraisal.

Shawn Huss from Talmer Bank and Trust was very good for a conforming loan I had.

I've done both private money to fund spec construction as well as an all in one (construction that rolls into a conventional conforming).  

Or are you just planning ahead and will have time to close a conventional/ conforming loan?

Is it possible for a property zoned Residential (R20) that is legally conforming to have a highest and best use as commercial via an appraiser?

In my town, we have what's effectively considered "allowed non-conforming properties" which are exactly like you discussed...multi-unit buildings in single family zones, etc because of grandfathering.

Have done a loan with them before and it was not conforming so hopefully not TGTBT. 

Unfortunately I am just now beginning my real estate education, so neither of these properties were good long term investments.I currently live in the National Capital Region (NCR), but I don't feel conformable investing in this high priced market.  

My Dad likes to buy these types of properties and turn them into rentals to collect the extra cash flow from the non-conforming units ... double bonus if it is in an area with college rentals (that tend to rent by the room) or airbnb.

Once you confirm that the AC conforms to whatever is legally required, and is functioning properly (even though it might not be strong enough for the tenants' taste), offer cash for keys.