Also the value (in this case) is determined by the NOI, so assuming it will be worth 2x, is assuming your NOI is thru the roof (which is can be, but it's not likely in the first 5 years).

I am just looking for insight from local MA realtors, attorneys or landlords regarding what my typical monthly expenses (if any) will likely be (I don’t mean one-off expenses like roof repairs). 

These include accidents (I recently had 2 units destroyed by fire), natural disasters (I have had two units each hit by 2 hurricanes), property management turn over (they sell or stop being as good, I have experienced both), or turn over of team (I am turning over at handyman and I suspect plumber), or just wear n tear of property (slab leak in poor location, sewer pipes rotted out (one unit this month), roof, foundation issue, etc.).  

It had some deferred maintenance and I put a new roof on and fixed a few things.

For example, on a recent project, Draw #1 covered the roof, demo, and trash-out.

During your initial walkthrough, inspect the property for any major issues such as structural damage, roofing problems, plumbing, and electrical concerns, while documenting all cosmetic and functional issues with detailed photos and notes.Once you confirm the property’s potential, finalize your ARV and calculate the repair costs using either a reliable estimator or insights from contractors.

The excitement then went through the roof and the owner wanted to do three or four at the same time and the next thing you know the whole ship went down in bankrupt.Just something to think about. 

On the rental property side we will go through another round of capex improvements, mostly driveways and roofs.

One or two appliances or a new roof can wipe out years of cash flow. 

Luckily I had war fund saved up for the HVACs, roofs and foundation repairs I needed.