My comments...
Sanding the cars is a BIG job. You will look like the "Tin Man" from the Wizard of Oz before you are done.
We have had SEVERAL people buy the car in a filed condition and try to sand it only to bring it back to us to finish (fix).
Rich is right, you can really screw the car up if you don't know what you are doing.
I would not be surprised by someone taking 200-300 hours to sand/polish one of our cars. Think of the money you could make seeing patients, clients, etc with that time. If you look at it that way, then you can just take the Jamo approach-- "it only hurts once."
Now, that said, years ago, Pat Buckley sanded his car by himself and it was quite beautiful. Frankly, it was more beautiful than anything else we at Kirkham had done to that point--so, we got better. Pat raised the bar for us.
Originally, we sanded the cars in 80 grit and left them there. Even our advertisement at the top of this page is a car that was only done in 80 grit. Then, like I said, we saw Buckley's car and we have since graduated to brushing our cars in 220 grit.
We do all of our work with a DA--all the way to mirror. We polish at 1000 or 1200 grit. If you want to paint your car, then, I would just DA the car with 80 grit and start priming and blocking. (Make sure the car is absolutely CLEAN before the first coat of primer or you will learn how to strip paint!)
Finer and finer grits obviously evolved into our now well-known mirror polish. Almost all of our cars now leave polished. Polishing is a monster of a job but nothing looks a good as a polished car. Like Larry Ellison told me, "David, I can't believe how much attention I get in your car! My McLaren F1, Ferrari Superamerica, and Bentley GT combined don't generate as much attention as your car!" That was probably the nicest compliment we have ever had. (He is a pretty cool, down-to-earth, car-nut type of guy.)
David