Helocs (as opposed to heloans) are interest-only for a period of time, usually 10 years, so during that time the monthly payment is lower on a DTI calculation than a first position mortgage with the same balance.  

Is this a building you see yourself owning for an extended period of time and/or if you were to sell the building will there be a satisfactory return on the heavy lift capex  investment that's necessary?

Period!

-  If so, then that total (for example...monthly debt service is $2,000 and you underwrite at holding for 6 months, then you factor in that you have a total of $12,000 cash that you will be putting into the deal over that 6 month holding period) counts towards your "costs" or "cash into the deal" that you need to factor in, correct?           

(That is completely legal although they will word it as something like a "refund for efficiencies")They will need to look over your policy.  

Scaling Ownership - Given our available cash and equity, what strategies would you recommend for scaling our property ownership efficiently?

With cash out refis, there is no market input on value.The time period since acquisition is also an issue.If I understand the numbers - $30K plus $440K loan plus $80K assignment fee - total “purchase” price is $550,000.I would assume lender is asking how is current value one year later $725,000 when you effectively paid $550,000 a year ago?

You would then periodically pull the ap up and "swipe left of swipe right" for business or personal trips.

Our plumber re-plumbs entire houses for much less than that, and if it's a simple leak you can find, you could be done for a few bucks.The 80's were the era of pinhole copper, so there's always a chance that your supply lines are shot when buying a house from that time period, but it could be something minor too.

Simple, convenient, and cost-efficient!