When you go to sell, Montvale requires a certificate of occupancy so this issue has to be resolved in advance of a sale.Although I am not a lender, I assume you will not be approved for an owner-occupied mortgage on 5-units if it is a legal 4-unit without some type of mortgage fraud whether in reported rents, units, or another legal document or representation (very very large issue from a legal perspective with multiple arrests in the last year for anyone playing fast and loose).As far as the DCA, I would recommend coordinating your work with the city with the DCA.

Seems like a lot of people are recommended them here. 

We were using a 4th (not on your list) but I cannot recommend them. 

If the machines are 15+ years old, I recommend getting a quote to replace them.

I'm a beginner as well, but have been reading this site enough to see the recommended (over and over) approach is to leverage your presumably un-tied-down youth to move every 2 years, each time using 3.5% down payments to buy multifamily buildings / house hacks. 

If that is a stretch as to your qualifications, I would not recommend this as it would with relative quickness go to the attorneys to move forward with drafting, inspections, title search, etc.

You'll end up in court with a lease agreement that says rent is $1, and the recommended tip is $1,999.

They also have calculators to analyze deals, and I highly recommend you start this as soon as possible, even if you are not ready to buy.

None of which I would recommend. 

What is the recommended R-value to use?