I have had the front end off a few times and it doesn't take too long, about 45 min. but when changing colors you may have to assemble the 3 front parts together which can take a bit more time. Doors take a little less time, and back end including tailgate can take about an hour, again 3 pieces have to be assembled. so with a few helpers, you could do it in a day easy.
I know Red, Blue, and Yellow are all painted on and black is a MIC (molded in color)
I don't think I would take my car in anywhere to have a panel changed. quite easy to do it yourself.