If you earned $500 p?

I would imagine that in your part of New Jersey, the extra income would be significant (maybe 12k per year?).

Personally, spending the extra money on a home warranty for rentals is a waste of money.

You might have a few dripping faucets and a toilet running occasionally costing you a few hundred extra per month.  

Do I care about the extra interest that will not accumulate or do I care less because I can acquire another property and someone else is paying the interest?   

@Gabriel BenavidezIf you are self-employed (i.e. active self-employment earned income separate from your w-2 income) with no full-time w-2 employees, you can set up a Solo 401k and then rollover your 401k funds once you leave your current job. 

If you have extra money to give away, I guarantee I can find charities that are in greater need than your tenants.I also disagree with small increases over multiple years or even over a one-year period.

meet with a lender and go thru the formal pre approval steps to know for sure ..if the 15 yr fixed payments dont work for approval - fall back on using 30 yr payments ( and then just pay extra to payoff the loan quicker)  

It took a little longer than expected, but totally worth the extra time.

In addition, should I pay the extra 600 to bring the rate down to 4.99%?