Questions on body work

If the car or any sheet metal parts have been in "Regular" Primer for 5 years, you'll probably need to sand back down to sheet metal as "regular" primer is porous and will let moisture get to the steel aka rust under paint. IMO I would strip/sand it all down to bare steel, apply an epoxy primer. Etching Primer is ok, you can do bodywork over it. Then regular primer over that.
I like the Epoxy Primer because it makes a non-porous "shield" over the parts and can be tinted close to your final color making for less coats saving paint n $$$