Unless you need to remover/repair rusted out parts, it sounds like what you intend to do is to strip the body down to a bare shell (like this:
http://dynacornbodies.com/body-shells/challenger/) and then rebuild the car from there.
I hope that's your plan, because, your apparent limited knowledge of how a car is constructed (based on your own statements in this thread), is going to make this a nearly impossible plan and be counter-productive for being a good project for you and your grandson. That said, everyone has to start somewhere, and you will both learn a lot from the project. However, removing pieces of a unibody car is a major undertaking and requires a high level of skill to be able to replace it properly.
In any event, I'd start off picking up a factory service and body manual for your car, or equally good, a factory parts book. You'll find out where pretty much every part of your car bolts together.