Not so short answer...This is an area of expertise for me. I'm an investor as well as a Realtor. Turning your condo into a rental is a great way to produce a few hundred dollars in additional monthly income. Some lenders will consider that you will have renters and adjust your back ratio (debt/income) to account for that. They will probably use their own rental data for that, not what you intend to charge for rent. You have enough equity (~19%), but you still need to be aware if an acceleration clause exists in your mortgage to include your 2nd mortgage, if you have one.
Regarding your new property, FHA loans don't require 20% down. If your credit score is good, you may only need 3.5% down plus closing costs...unless you want to put more down.
Feel free to contact me for additional info.