If you live off the montclair-boonton line you will have a direct train into penn station NY, it’s a very doable commute. I would try to live within walking distance from the station as having to drive & park at the station will just add more stress.

Montclair is a beautiful town but it’s gotten extremely expensive. There aren’t really any dangerous parts of town but generally south of Bloomfield Ave is less nice.

Bloomfield is cheaper but some parts are sketchy, specifically the downtown area around Bloomfield Ave. It’s a block by block thing so hard to say without visiting the area for yourself.

If you live in NJ and work in NYC you will be paying NY State income tax and probably zero NJ tax (since the taxes you pay to NY get credited off your NJ tax bill).