Best way to tell if you have air leakage is to turn on the unit and remove the return filter section from the unit. If you feel any air blowing out from here, you have a leak. You will be able to feel it and where it is coming from. You can seal it up with a good duct tape.
For those that might add the second a/s later, you can either have it tied into the duct system or just have it blow straight out into the bedroom. Just depends on which ceiling kit you buy. Be advised that if you want it ducted you will have to get inside your walls to run a thermostat wire. The ceiling kit style has the control knobs mounted on it, the duct kit does not.
