If you're going to do a solid color, I wouldn't bother stripping the old finish. If it was my guitar, I'd simply repair any dings, rough up & level the finish with 320 grit sandpaper, and start painting. Leaving the old finish in place will eliminate the need to do grain filling and sealing to give a level surface.
Someone correct me if they know better, but I believe Fender uses polyester on their Mexican products, so you won't have any compatibility issues with either nitro or poly finishes.
You can either use a random orbital sander on the top and back and hand on the sides (drum sander on a drill press works too) or heat gun. You can also scuff the existing finish assuming it's not badly damaged and paint right over that but if you want the tonal benefit of nitro then you have to strip.