Okay, well burning a spider corpse until it's safe to eat takes no skill - even setting up a fire takes no skill; and if it does, the ranger can spend, like, 1 hour instructing everyone on how to make one or even handle something larger like a bonfire or whatever - the existence of equipment to make fires probably makes this even easier, improvised fires just take longer to set up. I think if a ranger knows how to make improvised fires, he'd certainly understand how the use of equipment (flint and tinder) that makes the process easier would apply.

Actually doing improvised cooking and preserving of meat might be survival (that'd be important for attaining more rations on the go). Making it tasty is just knowledge (local). Tasty food doesn't preserve very long - preserving food is survival since it involves practical knowledge such as the curing of meats. Note that rangers have the survival skill and rely on it for tracking - I typically consider rangers to be the kinds of people who can go for literally years in the wilderness (barbarians on the other hand rely on tenacity and the help of fellow hunters/gatherers; while druids just use magic obviously). Rangers don't get magic until they're at the pinnacle of the wild man's lifestyle and well above bad ass in the real world (4th or 5th level?), so obviously Rangers are largely mundane.

They probably use survival to keep stocks of food preserved at hiding places (hiding something effectively might be a knowledge: geography check or search check or wisdom check to get creative with the procedure; largely hinges on circumstance), handle animal to tame wild animals and survival again to track prey and set up simple traps (elaborate traps are craft: trap making).

Practical knowledge is improvisational and rooted in common sense (all based on instinct/improv). So, yeah it's all Wis pretty much. Most common sense is learned but others are covered by skills like survival. That's my take anyway.

Maybe, as part of knowledge (local), you'd comprise common skills that can be bought - some could include business sense (how to observe supply/demand and ply your trade in a region from a book standpoint; actually selling to specific customers would require some social skills - mainly when you need to compete with other sellers), social behaviors of different humanoids (this probably is just general, doesn't need to be bought), and of course, cooking.

Cooking isn't worth a skill point considering you can make a lot more money doing craft (armor smithing) or what have you. Also making something tasty only exists for RP worth unless you want to run an entrepreneurial game involving a chef that works for a restaurant whom needs to produce high quality food on high cooking rolls.

As for the spider - if the spider had a poisonous attack, then it's possible that lack of knowledge: nature from at least one character might cause the party to consume the poison by accident. Although they'd probably know to be careful anyway, if they knew that the spider used poison. Even with poison consumption, you could simply rule that craft: alchemy checks can be made to experiment with making new potions based on the ingredients you already have. In this way, you can apply the rule to making an antidote for specific poisons. In the case; (size category) spider poison or 'complete name listing of monster that happens to be a spider' poison. What the antidote works against in regards to poison would be noted by the GM since it's probably a custom item that's not in the books. Antidotes are also mundane.

With the above ruling, craft (alchemy) could easily be ruled as applying to all characters - but only those capable of magic can make magical items from them. Hence, all alchemical items in the books should be noted as either magical or mundane. Ie. a smoke stick would be mundane but a tangle foot bag would be magical, since it's beyond sci-fi to allow a plant to grow quickly into massive vines that wrap around legs tightly and hold them in place so that said victim can't move (unless the bag just uses adhesive).

This is all my perspective. Some things are difficult to accomplish in real life but not covered by skills or abilities in D&D. So yeah, it takes some merit to allow D&D to offer more freedom like a more free form RP.