Fender channel help

I decided, since it is my first time rehabilitating a fender, to drill out the spot welds and take the thing apart. I got the channel off last night and it looks like it will clean up decently. My plan is to get the other pieces off and take everything to an auto skill shop at my employer and bead blast everything clean. From there, I plan to epoxy prime the hidden surfaces and put the parts back together. Then I will epoxy prime the whole fender assembly and spray the inside with PPG urethane. Do I need to seam seal where the parts go together? How much should I pry up the lip where the channel goes at the back of the fender? Right now I just lifted it up a little bit to get the channel free. Sorry for all of the noob questions, but I would rather ask a dumb question than do a dumb thing.

dartpic.jpg