I think if you can power 100 watt lights, get em... I think they should put out more light... and I would say yes on the rear lights. They may not make much difference normally, but any backing up in dimly lit areas will be a lot easier...
As for bed liner, go for it. I can't make any suggestions about the fenders and all though... when I make up my bumpers I'm bringing them up on the sides to get a little more clearance, and I'm hacking off the little part at the bottom just behind the rear wheels... the little chrome bit. It does nothing but make the body lines flow more, but I like the idea of having the front and rear up high. Besides, I'll be running custom bumpers front and rear, so it'll give me a couple inches of clearance around the wheels... I will probably make some sort of overriders or guards to mount on the bumpers for city driving... that way if I hit a little Honda or something I can destroy the bumper rather than the wheels... or worse, drive up onto the hood of the other car...