The MORE UNITS you own, the less losing a tenant will IMPACT your monthly gross income = BOTTOM LINE.

Your best bet would be to do a tear off of the existing roof, inspect the wood planking for rot then re shingle it.

I would highly recommend using one of the Providers on here (I use @Dmitriy Fomichenko and have been very happy with his services) , they are not directly allowed to promote themselves on here, but just look at the signature lines and you can tell who they are. 

Until he learns the regulations he should not be dealing directly with tenants.You are responsible for learning your state regulations and can usually find them on line.

Gentrification is a powerful thing and having seen it up front, I wouldn't bet against it. 

Thus, I need someone competent to do a thorough financial analysis to help me understand where the swing points are in the tradeoff where one option would make more sense vs. the other one.Something along the lines of:https://www.nytimes.com/interactive/2014/upshot/bu...but which also incorporated my current investment property holdings.

How many feet of line will they be running?

The bet offer we can find through a bank is 30 years at 4% interest with 25% down.

Next, depending on your credit, I would look at a simple line of credit.

I also investigated a home equity line of credit.