69 Camaro quarter panel(s) and rear shelf replacement

[1Bad68Cat]

Began replacing full quarters and rear shelf on a 69 camaro. Have a few questions.
1. Where are the spot welds holding the lower portion of the quarter panel @ the tail light panel? Will the tail light panel need to come out?
2. The repo panels I'm using do not have the raised lip along the drip rail like the factory. Any suggestions on how to replicate this feature on the repo panels?
3. I'm replacing a panel @ a time to maintain panel alignment. Is this a good idea or should I cut all the panels out and install/adjust the new panels to each other?