sounds like youhave the basics down, i usually prime at 180 grit but that's just me, i've done 220 on colors that i'm worried about..
just something to let you know before you spend a bunch of time on parts. my bro just picked one up and were' redoing the whole thing... but anyways. found new doors for under 100 and fenders for 75. so might be worth just buying new to save time and effort, then you could seal and spray then and save time and material also.. bed sides are about 250. just a idea. you can get away with just replaceing things on these because parts are cheap.