OK, you need to calm down.
You need a City Navigator NT DVD to get the maps on your computer. I think I've heard that you can just ask Garmin and they will send you one for free since you already paid for the maps which are pre-installed on your GPS (yes it's ridiculous not to just include it). You will then have to go through the unlock deal. It's been a long time since I've bought any maps so I'm not sure how it all works these days.
You shouldn't need a data card unless you are loading additional maps to the unit, like Topo.
If you have the maps on the computer you certainly can "open some map software, click the roads you want to ride, create a route and transfer to gps", I do it all of the time. You didn't give yourself much time to figure it out before your trip.
From what I understand, the guy who came up with the TAT doesn't want to put himself out of business by selling easily copied/shared GPS files of the route.