Interior Cab update

[Texasduffer]

I don't usually do a lot of the work on my 70 LWB myself, but I'm ready to strip the interior and sand the surface rust, prime/rustproof, Dynamat, and paint the cab interior and I want to do this part myself. Couple questions:

1. In ya'lls experience, what's the most efficient tool to sand down the interior on this dude? Grinder, drill, orbital sander...I'm open to anything.
2. What's the best coating to put on it after it's sanded to keep off the surface rust before paint or Dynamat?
3. Are any of the brush-on sound deadeners as affective as the peel-and-stick products like Dynamat? I'm most familiar with Dynamat from my stereo days, but I'm open to a better/better value product.

Any suggestions would be helpful, thanks to all....