rust issues

I have a big wire cup on my right angle grinder, it gets a lot of rust cleaned off in hard to get to places, also great on the inside floor pans, inside truck floor. I use it on the inside of trunk lid pinch welds at the edge of the lid., bottom of isdie of the door pich welds, etc.... I clean as good as I can, then use "ospho", its a phosphoric acid type solution, costs like $10 a gt at true value auto. be sure it is totally dry before applying any primer, and realize an acid based epoxy might cause a problem with it.
most of us don't have a small sandblaster but obviously great for those hard to sand spots.

l ike he said, best to take the entire to bare metal, any pitted areas I like to treat also. i'm NO body expert, but learned from experience scattered over the years plus I will ask real body men their opinion. opinions run the gammet!!!!!

not sure what the question is with "skeleton", but the factory dpped the car in primer, it has seal sealer around joints, then it was painted.

all body guys will tell you to clean it to as bare and clean meta as you can, then go with some sort of epoxy/ self etch primer as a base. body guys I know use NO rust killer or preventative. probably because if there is a reaction to it, then the paint supplier would not be liable?? they do clean with then with the epoxy. and go from there.... my opinion.