I will parrot what everyone else has been saying...parking is very easy. The port is well marked and Disney has a huge presence there so finding you way around will be easy.
All you have to do is pull up, drop off your checked luggage and then make your way to the adjacent parking garage. Once you park, it is a short walk to the terminal.
Parking is a bit on the pricey side, but it is close, covered and secured making it worth the extra coin.
This video is a little long and boring, but it takes you through the whole process.
When you get back, you will grab your luggage at the port. If you have a good deal of it, there are plenty of porters there waiting for you that will take your luggage all the way to your car. From the time we get through customs until we are in our car heading home is usually less than 20 minutes.