If you make the minimum monthly payment on time every month, and pay the entire amount off before the end of the promotional period, you will pay zero interest - essentially a free loan.

It's a historic district and is 5 miles away from a large metro area (across state line).  

Essentially I would like to build a stream of $20k/month.

So you're saying the proforma is just essentially a waste of time and that instead of arguing with the seller over numbers, I should just plug in my own best guess numbers?

A number like that means that essential one thing can go wrong per year.  

I get that you would have clients (essentially a book of business) and places under contract that get you a cashflow, but how would selling this business work?

., what factors or metrics are "essential" to making a smart multi-family real estate investment decision?

Note however I had to have the 25% up front, and then essentially got reimbursed those funds at closing.  

The less expensive of the two towns in what is very possibly the best school district in the state, commuting distance to the 128 corridor or Nashua/Manchester, excellent demand.  

I appreciate all your feedback and assistance.The house is in the Historic district, build in 1901.The contractor is not licensed but is very experienced.I seen his work and is very knowledgeable and experienced.Based on those notes and the feedback provided in this forum I know there is alot of work ahead.Based on those notes, @Keith - Dimension of the bathroom 8FT 3in by 5 ft 3/4 in., plastered walls.