Try searching online for "traveling contractors" or "nomad contractors" along with your location. 

With the new Business Owner/Investor continues to pay the Mortgage with a service company so payments Principal and Interest go to the Bank as scheduled per the original MortageHow can the new buyer do a wrap (#subject to) with the #first #lien for the underlying mortgage where as the Seller equity is in the second position?

I'd suggest checking out some online calculators or spreadsheets tailored for real estate ROI analysis.

Full disclosure - I'm a mortgage broker actively placing private money construction loans. 

For a reputable builder, ask for recommendations from friends, check online reviews, and visit recently built properties in your area for ideas and potential contacts.

Vacasa Guestworks(partial MGMNT model) says their fee of 12% is almost covered by the fact that THEY will pay the Airbnb host fee   Also they will handle the tedious filing of monthly taxes as required by my city/state regulations  I’m not scared at all to handle the online listing and am not keen to pay their 10-12% fee.

If you're looking to leverage a mortgage, plan on a 25% down payment for a condo/townhome... the vast majority here are non-warrantable. 

@Bryce Carroll,"mortgage would be accounted for by 2b"?

It kills many birds with one stone (you get a place to call home for a bit, while others pay the mortgage and you continue to build equity). 

I would not put extra on your mortgage.