Amazon sells a drill attachment that is just a hard clay mold (3M I believe sells them also) that is designed for decal removal, but will work well for removing old foam-tape style adhesive as well. Good luck!
Both of those above mentioned systems work, I used the rubber wheel thingy from Amazon and it was great.
As for the bumper, many places in the UK can plastic weld the bumper back together and fix it.
In Canada here the color of the car is on our ownership. When I was younger I was pulled over and the cop asked for my ownership and license. When he came back he said that I had to go get the color changed on the ownership because it was wrong. My car was Grey and the ownership said GR, my only guess to this is he thought it meant green.
Now finally the sticker bomb question. How would a companies wrapped vehicle for their business work. Some of these trucks can very intricate in the design showcasing several different colors and patterns.