1967 Cuda..........
As you stated.."I got frustrated and deshoveled when I ruined the body by trying to bondo the dings and dents myself, having never done it, and with no help but for some scattered advice: within a couple weeks, rust started growing from under the dozens of bondo/primer spots."
Don't beat yourself up!!! Primer is not a top coat and will absorb water.
My son has painted 2 of his girlfriend's cars in the driveway and they came out great. He was somewhat self-taught and really studied and read a lot of books on the subject.
One body shop owner took him under his wings when he realized that he could paint better with a spray can than some guys could with a gun.
The only problem now is that he works only on stuff that he wants to do.
No production style scuff it, shoot it and hurry on the the next one and see how many shortcuts you can get by with deals.
