Hi @Dylan Wang, welcome to BP!
The plan you have put together sound great. Start with house hacking and then move out. I personally plan to do the same in the very near future for my personal residence.
That being said, I have lived in the area (Clifton/Passaic/Garfield) for about two years now and what you're describing (15k taxes for triplex) could not be a great deal. It really depends on many other things such as the purchase price and I would say primarily - location!
Passaic has nice and not so nice communities. The statistics on average are low, but there are areas where it could be a great investment. I would share all of the numbers here (purchase price, rehab estimate, rent estimate, other expenses) and we'll be able to give you a more accurate picture.
If you're just getting started, then I would recommend to start with the Ultimate Guide to REI and Episode 200 from the podcast. That will give you some direction. I mention the podcast because it will teach you that you need to decide what kind of properties do you want to own.
If the property is in the not so nice parts of Passaic, it may not just be a bad financial deal, but you could also end up with tenants that may not be the most pleasant to deal with, let alone live alongside for 2 years.
There are a lot of important questions you need to answer, but don't fear - BP is a great community so you're in good hands.
Regards,
Alek