As far as occupancy limits enforcement does happen but it’s not super common and every case I’ve heard of for enforcement is due to neighbors complaints  typically noise or too many cars.

Conventional rates may be higher, but depending on your situation you might be better off with conventional due to variations in mortgage insurance. 

I am a realtor in NY and NJ, and although I don't wholesale most of my deals, I source off market properties to developers and fix/flippers.

Can I find a lender to refinance an investment property that is fully paid off?. 

DSCR loans are based off of down payment, credit score and either actual or market rents so it helps to supercharge an investor's real estate goals and net worth.

Found out later that he is a serial non-paying tenant that managed to keep judgements off somehow.

I’ll have our property manager’s contractor handle this (or do you think I’m better off hiring a plumber?)

The earlier you start in your RE journey, the better off you will be in the future.

You could keep the property off market and get it sold in a much easier manner. 

If you are starting with under $100k, then you are probably better off investing in a fund, but revert to #1. 3.