RE: step order
I don't think it really matters what order you do it. I see a lot of people paint first and a lot of people cut first. I prefer to cut first. If I cut first then I can dremel the cut edges to smooth the cuts without worrying about messing up the paint. Hope this helps.
Best advice, take your time cleaning the body and make sure the masking gets into all the grooves so the paint doesn't run along them under the paint and ruin a great paint job.