I've used a combination of cut and replace, soda blasting (which does get rust out of pits), Picklex 20 (which is a fine rust converter/protector), Evapo-Rust, Navel Jelly, Eastwood Rust Encapsulator, and Zero Rust. I would choose Zero Rust and Encapsulator over Por-15 any day. Neither contains Iso's and can be sprayed easily and without fear of killing yourself. Of course, total eradication and/or removal of rust is ideal and should be your goal and first priority but that isn't always practical or even possible. Water and oxygen promote oxidation. If you can't remove the rust completely then starving it from moisture and air is the next best thing and that's what these products help do.
Picklex 20 is great if you want to leave metal bare but unexposed from the elements for awhile - preventing flash rust. It also works good for converting any traces of rust that may remain after you think you've removed it. Though the active ingredient is the same as the green hardware store stuff there are differences in the formula that make it superior. Evapo-Rust and Navel Jelly are amazing all on their own. Encapsulator and Zero-Rust are best for areas not intended for top coating - frames, undercarriage, insides of doors, rockers, etc. For exterior panels I'd sand the surface rust and, if possible, media blast to clean out pits. A rust remover or converter (for trace) followed by a coat of epoxy will then give you a good base to build upon. Cancer though? It's gotta go.
My two bits...