So, they make different tools to make a flange to glue to, the cheaper tool is basically a set of vice grips with a special jaw welded in. Or they have a tool for on an air chisel. Pretty sure there are other options these days. Never glued a panel yet but might give it a go. There’s a big auto body repair supplier in town that I can get the glue at.
Paint related, you don’t absolutely need a spray booth, but even a temporary wood and plastic structure (
@gwaii did it that way) would help with keeping bugs and dirt off the wet paint. Solid colors are the easiest. Use a HVLP gun. I helped a buddy do the bottom of a boat a few years back with a Harbor Freight gravity feed HVLP and it turned out alright. Little bit of a learning curve, but it works. Single stage solid color is the easiest, prep, prime, spray, done. Two stage solid and you have an extra wet sand and clear coat at the end. Metallic gets tricky, have to make sure it stays well mixed and be careful with spraying.
Prep is absolutely critical. Sand scratches WILL show through. All repairs need to be sanded as perfectly smooth as you can manage. Make sure you remove all dust. Don’t do the bodywork and sanding in the same space you’re painting unless it’s outside.