The rear window can be removed and put back in similar to the rear cargo windows. You can fully sand and repair the rust and hopefully you wont require any welding.
This video shows how to pop them out with plastic scrapers:
The front headlights can be popped out pretty easily to get better access at that dent in the front but unless you're experienced in body work itll look like a DIY job.
I'm doing a full body respray on my 80 right now. Total cost is around 1600 dollars with a huge time investment.
If the back glass is original (or a replacement that was correctly installed) the glass will be glued to the weatherstrip and the weatherstrip will be glued to the tail gate. They are harder to remove than you think.