You will need a RMLO to modify any residential owner occupied mortgage. 

I’m Christian Dozier, a licensed real estate agent with The Nate Evans Group/EXP Realty, proudly serving the Champaign/Urbana area.

I use realty postcard.

I'm assuming you're referring to residential (SF and MF) properties that are vacant, is that correct?

Two factors at play here.1) STRs generally appraise as residential homes, not as businesses based on multiples. 

BPG Residential 

. • The real property that is being occupied includes a residential dwelling.• An unauthorized person or persons have unlawfully entered and remain or continue to reside on the property owner's property.• The real property was not open to members of the public at the time the unauthorized person or persons entered. • The property owner has directed the unauthorized person to leave the property. • The unauthorized person or persons are not current or former tenants pursuant to a written or oral rental agreement authorized by the property owner. • The unauthorized person or persons are not immediate family members of the property owner. • There is no pending litigation related to the real property between the property owner and any known unauthorized person. 

If you're looking to expand into the Miami residential market, you could always purchase this condo with your BTC. 

What are the typical pre-payment and mortgage payment increase restrictions on a fixed rate residential mortgage in the U.S.A.?

Yes, if anything its easier since no residential restrictions. savvy participants.Harder because you have to know how to present a property, typically have to spend on chase costs prior to assigning.