Yes, it offers a low barrier to entry and high cash flow!

I am undereducated on most other states but I imagine CO, CA, TN, NY etc all have thriving locations as well, just unsure about their regulations and returns especially in the high tax states.

I highly suggest that you try to attend your local REI networking groups and meetups.

High W-2 wage earners are generally more lender friendly as it's the 'most' consistent and/or easily documented.

Tenants that habitually pay late are highly likely to become more problematic down the road.

Highly doubt it But I could see a 20% pullback ... 

Also, is there a nifty tool to calculate incremental return of additional principal payment?

Conventional wisdom would have said with rates so high (comparatively speaking to where they were) demand and prices would have lessened in more places and more quickly but in many places prices have held steady even as inventory creeps up.

The first is the interest rate, my guess from the information you gave is that the loan is about 6% which isn't all that bad, but high enough to consider paying it off versus investing in some S&P 500 etf (depending on your marginal tax rate). 

Highly recommend if you want to save a few shekels.