Yup, which is why I modded one in using same approach as the charcoal kiln - making something portable is impossible without metalworking, but you should be able to construct one out of stone.
Neither existing recipe for forges or crucibles uses these (the current crucible recipe is sheet metal attached to a steel frame? seems excessively off the mark). I imagine that’s because while a need for those high end tools is true for proper modern metalworking, that kind of crafting is generally gated from the player. For melting down scrap metal into ingots and beating them into a shovel like a ye olde timey blacksmith, I don’t see a huge issue out of using ye olde timey facilities. And if there is an issue, I’d suggest it be split into tiered quality levels of forge/crucible rather than cranking up the requirements for blacksmithing, when blacksmithing is already not all that generally useful in a ‘normal’ game.
Everything else in the fabrication line, and a pile of recipes that require a swage and die set are autolearn. You can build forge, anvil, crucible, tongs, chisel, and know that you need a certain size die to make a certain item, but you don’t have the knowledge to make that die without a book.
Keep in mind, I’m in a (nearly) book-less situation to determine the line between what should be relegated to books (like almost all of electronics or chemistry) and what should be learnable on one’s lonesome. I’m firmly of the opinion that relatively simple basic tools (and the tools to make them) should be autolearn with a high enough skill, and most other things should absolutely be relegated to books. For example, pickaxes are not autolearn, while a collapsible entrenching tool is, and I’d argue the two should be switched. I can already make a shovel, and an entrenching tool is just a luxury.
That’s the general intent. I’d like to move the clay to the brick kiln rather than the charcoal kiln, then make a constructable alternative to the portable one. I’m not sure why the psuedo-item isn’t working, but I haven’t done much research on it yet. There may be a hilariously simple explanation.
I wouldn’t add a recipe to make sugar proper, just tweak some existing recipes to accept sweet items as an alternative when it makes sense. For example, the deluxe oatmeal recipe uses a sweetener and has 25 options. Sweeter fruit in particular can be dried and ground up or fruit juice can be boiled down into a syrup (and apple cider syrup in particular was used a lot along the east coast before cheap cane sugar became available). Rhubarb should be usable in a recipe other than dried fruit without access to proper sugar.
Yeah, that’d probably be the end implementation. Though, the constructed forge’s code is 10 kinds of wonky. The way it works (at least on the build that I’m playing), it holds a single number for how much charcoal’s inside it and you only have the option of overwriting it with however much charcoal’s in your inventory (up to 100). I forgot to add that in the OP (probably because I haven’t really tested it much beyond making a 
face at it) but it’s pretty strange.
I’d love that, but it’s far beyond my ability to do. In the interim, I just don’t think “it’s too easy to do one flour craft” is as big a problem as “it’s waaaaay too hard to batch 20 flour crafts” and would rather err towards making it too easy.
Again, .05 item spawn rate with size 1 towns. The idea of farming only being viable in a world with enough food where you don’t really need to farm is a strange one. I’m actually really anxious to get a farm going because of how little food is easily available in my game, and with almost 90 days of playing and travel spanning multiple map pages, I’ve found exactly one plantable seed, which was hemp and off a zombie. I’m not sure what you mean with the plant selection process - the idea would be you forage some wild vegetables, then cut some up to make a few ‘wild vegetable sprouts’ which are basically wild vegetable seeds. Then those would use the regular planting/growing framework except ideally there’d be a tag that reduces the plantcount such that found seeds are generally better. Wild veggies/wild herbs aren’t specific anyway, so some variety is to be expected.
Buckwheat could just be special cased to not take fertilizer if that’s important, but properly handling that really falls into a broader farming overhaul with like crop rotation and fertilizer types and plants that maintain a higher epoch when harvested.
Yeah, I’d like a more involved sapling process in general - maybe make flower pots of various materials and use them to move saplings around, or make constructed flower decorations out of bluebells/dahlias.
Huh, I didn’t realize improvised shelters covered comfort and warmth, for some reason I thought they only provided a roof over your head. Well, that covers that.
The stock one has a 2.5 foot diameter, if I did the math right. I’ve never seen one that big outside of video of a food processing plant, and I was under the impression that the vanilla funnel was just a regular kitchen funnel (since it’s treated that way in the loot tables). If it’s intended to be specifically a rain catching funnel, it’d need to be pruned back to only really being available in milsurp or survival stores and the description could be made more explicit.
You can make a survivor machete out of a makeshift machete, a 0 skill craft that takes nothing but a blade and duct tape. But even if you eliminate that, I’d say it’s still too easy. What I’d suggest is keeping the materials as-is, but require some actual forge work like the naginata rather than a piddly 20 charges of a soldering iron. That’d keep it relatively easy without being a free high end weapon.
