The metals last forever. The Ferric Oxalate, as you've already mentioned, does go bad; I typically mix a new solution from powder after about 3 months. You don't mention any developer--I use Potassium Oxalate--but this will last nearly forever, too. I haven't used EDTA as a clearing bath for a long time, but IIRC it lasts a long time.
I have had some old bottles of Platinum develop crystals in the bottle. Nothing I could do to permanently put them back into solution. I ended up sending it back to Bostick and Sullivan so they could put it back into solution for me.
Dennis