We usually use the 528, it's a more direct route, if one can use that term so loosely. The fact is, the tiny cow-town of Orlando grew up in hiccups, so there is barely any grid or rhyme or reason to the streets and they way they are designed.
I'm warning you, rush hour can feel like California. And since most people are driving rentals and are from out of state, there's a bit of confusion going on. Stick to your guns and breathe deep. Also be careful to not get sidelined. You'll be passing some of the largest billboards ever and some other amusement parks. You might want to rubberneck. Focus, I tell you, focus.
If you have a GPS, use it.
The "Real Mr. Toad's Wild Ride" will begin when you hit the resort itself. Disney has so much control, they even make their own signs. Big purple ones. Fun...but not always the easiest to read. Luckily the Port Orleans Resort is near Downtown Disney, so look for signs to the DtD, and you'll be closer to where you need to go.
I hope that makes sense.
Oh..and have a good time. I love having a car when I'm there, but use it to your advantage. Leave early when you can, but don't leave with the crowd...you'll be stuck with the mass exodus.