Plenty of opinions on these issues. None are wrong.
I have a 2x gun. If I was buying new (from scratch) I'd get a 3x gun.
I have an air driven high speed drill. It gathers dust while I drill with my cordles 18V drill. I don't like being tied to a compressor and/or hoses unless absolutely necessary.
I have always found manual squeezers to be very cost effective tools. I have yet to need an air driven one. I think I could probably rivet just as fast with a manual squeezer as with the pneumatic one, and even better, no compressor or cords required.
The C-frame tools from various vendors are all similar enough that it isn't an issue.
You'll need files, rulers, sharpie markers, snips, drifts, a center punch, etc. I have a boatload of tools, and they all come in handy at some point. A drill press and bandsaw are very helpful, as is a benchtop sander.
Old doors set on sawhorses make great workbenches. They are extremely portable and take up very little room when stored.
Priming? Honestly, you'll go broke using rattle cans. They just don't contain much sprayable material. They are great for when you have one or two little parts to prime and don't want to clean up, but otherwise, they are pretty inefficient. The exception would be if you only primed faying surfaces (i.e. places where one part contacts another). You wouldn't need a lot of primer for that.
2001 RV-6 N46KB