I can keep the current property tax rate and will not be reassessed at current mkt value.

Typically these need now to be in a rated shaft and just not insulated. 

We bought it with a HELOC on my mom's primary residence for the first $40k, then hired a contractor for demolition and major renovations, did cosmetics ourselves and used more heloc money totaling $60,000. 1 year later we listed it on VRBO and AIRBNB and refinanced the $100000 into a fixed rate mortgage.

In my experience like other things you get what you pay for. if you go with the companies that are charging super cheap rates - 5%, $100/month or something like that they don't have enough income to sustain a supportive team to actually help you manage your home. 10% is the going rate it seems in the city and that is where the better companies tend to exist. 

Another approach could be to use LPMI, which rolls PMI into a slightly higher interest rate, potentially saving you monthly PMI payments.

Property values continue to rise, enhancing its investment potential.

Property values continue to rise, enhancing its investment potential.

Most tenants stay for 2 years bringing our vacancy rate to 1.9%) 

Quote from @Tim Delaney: That seems like quite a jump in rate!

Here's a bit more in detail about how rates are calculated for DSCR loans:1.