I wanted to install the fender flares on my T-Reg too, but when I showed my wife some pictures she didn't like them... I think she didn't like how the rear flares are split into 3? parts.
When I thought about it, she had a point and I changed my mind about them as well (hey, they can be right sometimes!)
You definitely need to paint your lower parts. One guy who did a "wide-body" project with his T-Reg had the flares blended with the body using fiber glass I believe. It made the t-reg look as if it had a wider body that it actually did, instead of having flares added onto the body. Would've been a nice car, had he not used an ugly front/rear bumper kit.
Dunno if you're willing to spend that kind of money to have the flares blended with the body.