I do not recommend sand blasting because of the risk to your lungs. It might be OK for small things, like steel wheels, or cabinet blasting small things, but sandblasting a whole car or truck is both a health hazard and will leave sand in places that you will never be able to get it out of.
Watch some YouTube videos about
soda blasting. That's right, baking soda! It's a differnt grade than what you have in the kitchen, but it's the same stuff and it is not toxic! It will not harm glass or chrome. The residue should be carefully rinsed off with a weak vinegar solution (because baking soda is a base). Then you can use etching primer or whatever to prime the metal.
For the record, I've never sand blasted or soda blasted anything, but I have talked to several people who have (I was restoring my 66 FORD Galaxie). So I really am not speaking from experience. But, I believe what I have written is correct because I could not find an autobody shop in my city who offered sandblasting - said it was too dangerous and messy. There were several people who offered soda blasting.
On another issue - Rust Removal -
small parts can be soaked in Evapo-Rust (a non-toxic chemical which can be reused) or you can use an electrolytic process using a battery charger. Both will remove rust at the molecular level.
Back to the issue of paint removal down to the bare steel. You can find good info about how to use the 7" sander at this link.
http://www.autobodystore.com/strip_&_paint.shtml
This is the home page for that site:
http://www.autobodystore.com/home.shtml