My experience with the cooking skill is that, since cooking (usually meat and water) is more or less essential for survival, and something you’ll do more or less everyday, it’s almost guaranteed to be your highest skill. I usually wind up with a double-digit cooking skill and nothing much to do with it, save for the relatively rare occasions when some chemistry needs to be done. If you’re going to split off chemistry into its own skill, that’s not entirely unreasonable… but you shouldn’t do that before you add something else to make high levels of cooking worthwhile, given that there aren’t many hard recipes out there. Maybe hold off on the split until the tool/crafting quality system is in place, so high levels of cooking (and better cooking tools) actually get you better-tasting food?