Mike here from Robopromo. Definitely look into reversible bumpers. They can make life a lot easier because you don't have to take them off each time you need to change colors. We can supply you with the pre-sewn material for that and we have an instructional video on how to create them. Here's the link for that video on our website:
http://www.robopromo.com/category_s/1830.htm
To answer your question about how to attach a bumper, you can get a visual for that near the end of our bumper fabric upholstery video. And here's the link for that one:
http://www.robopromo.com/category_s/1828.htm