This is a fun topic for me, since this is where I was several years ago. First: Your income is not $600/month. I moved out of a condo situation with almost the same numbers, and only recently have been breaking even.... there is maintenance, vacancies, and other costs. So maybe your income is closer to $400... but you can tell the bank it's $600.
Second: If you are going to rent out the condo, get it rented by November or December... that way it will show up on your 2016 tax returns as a source of income.
As far as counting the income.... I've been told both things as to weather it will be counted or not, so I'm guessing it depends on which lender/broker lets it count, you might have to go to a mortgage broker to find a lender that will count the income from the house you area leaving.
3rd. Refinance? My thought is no, don't refinance. At this stage of the game, cashflow is king, and if you refinance and it puts you back into PMI, you'll kill your cashflow. In my opinion, it would be better to save up for the 2nd property since you really don't have to save up that much to owner occupy.... pick up a second job if you have to.
Last thought: Condo's often do not make the best rentals. Two conclusions: Are you sure you want to keep the condo, or is there a better place to put that money? Also, what are you planning to buy next? A duplex is a great way to go, and you can count the income from the duplex when you are qualifying for the loan. I think it's common for people to buy a house/condo they want to live in, and then treat it as a rental later, even though they never would have bought it for a rental.... Like my first house that I still have..... so look hard at the condo compared to other investments when deciding to keep it as a rental.
I hope these thoughts help.