I’ve done 1 rental property and sold it to gain capital and did 1 flip that didn’t go so well so not 100% experienced to say the least.

If it’s making $10,000 a month, no triplex is going to earn that much.  

I think in the past, I've let what I "know" get in the way of what I can learn so this time, I'm just going to learn everything.

I'm surprised someone verbally told you you can convert back to a duplex and didn't tell you that you must get permits.from what you are describing it seems the town gave you a hard time because you didn't get permits, I don't know that you have any legal standing to go after the town,  again, I am not an attorney 

With the down payment you're putting down (assuming it's at best 25%) with current interest rates, you're maybe going to be scraping a couple of backs cash flow on a Class C+ property. 

You might want to check out listings in your neighborhood to get an idea of the going rates and what amenities other hosts are offering.

It is very simple and cheaper to set up the LLC in NJ vs NY ($50 vs $200 when going on the state website) what is still an open question is I also need an operating agreement for the LLC once set up, wondering if that is also free as part of just getting the LLC set up on the state website or if I need to use a lawyer or a legalzoom type of service to do that.

This is exactly what I was looking for and gives me confidence that I can go after that deal. 

But tax wise just here to note if you buy a 4 unit as a primary when you go to sell (if you meet the requirements) only 1/4 of the gain could be excluded under the 121 primary home sale exclusion.

It's going to give people so much hope.