Welcome to the forum, so you're starting off with the fenders but I assume eventually you will want to do the whole car? If yes, then have a look at this forum, https://www.autobody101.com/forums/index.php?sid=f044bf1f351a02abe241234902095df9
So much good info on there and active pro painters that will answer questions. Chemical stripper works well if it is the real stuff, not the Dolphin friendly stuff, it is extremely toxic and there is always the danger of some of it getting into the seams and ruining the new paint job. A paint stripper heat gun works well as does a power sander, if the fenders will sit in primer for a while then make sure you use 2 part epoxy primer. For small jobs like the fenders you could use the 2k rattle can version, it is quite expensive for the amount you get but you can't get any more convenient.
Applying 2k epoxy primer, paint, clear coat with a proper spray gun requires a large outlay of cash for decent equipment and the learning curve is steep.
Take your fenders down to bare metal, 50-80 grit, the primer needs a rough surface to grab onto then clean the metal with detergent until a white cotton cloth comes away clean then do the same thing with thinners then again with one of the "final wipe" products. Two coats of 2k epoxy primmer will seal the metal so rust doesn't start again.