I already plan to have the common wall with double sided studs, 1" air gap between the two and rockwool insulation but wondering if adding double drywall with green glue would provide enough ROI with extra rent.

C-Corps get taxed at the entity level AND when you distribute profits -- that's double taxation, which kills cash flow on deals where you're cycling capital fast.

I am also in PA and I think that you are talking about is what in my market we would call a "double block".

If the property has been held a long time before it was sold to you, property taxes can double or triple on a property. 

I mostly do a double-close or close on my own though. 

Double down on networking.Upstate NY is very relationship-driven.

Currently, I have a double major in finance and real estate, but I don't have much actual experience outside of the classroom. 

Just double-check if that solar payment is actually in your PITI or separate - seen that flip deals completely.

The kind of multi-family your are most likely to find is locally referred to as a "double block".

I am concerned with option b just because the interest rate would jump from 3% to 5.7% and over the length of the loan I would be paying double the amount of interest compared to the HELOC.