THe stop and fix are fine. Stop is fine until it is no longer acid. If you use indicator stop, that is when it changes color.(posted 8953 days ago)Fix is supposed to have a 6 month shelf life after mixing. This is for Kodak Fix (powder). I have a bottle around that was mixed 1 year ago (3/99) and I have some very old rolls of film, unexposed. So I tried the fixer. Works fine.
As to the developer, is this the stuff as it comes from Kodak? If so, it should be fine. If you diluted it, I would toss it. For keeping the stock longer, either squeeze the bottle to eliminate air, or use something like Tetnal Protectan spray which displaces the oxygen.