I definitely think that food placed in stockpiles or crates that are underground should rot slower, since that’d encourage cellarage simply by mechanics rather than needing to allocate anything specifically. Flag the stockpile/container at creation time and check them every day or so, to keep the logic simpler on the actual mechanics. Rotten food that isn’t used for anything should disappear after a couple of days too, just to keep the world tidy.
This is a good idea. I know brewing is planned, but I’m not sure what specifically is planned for it. I know wheat and pumpkin can be used in beer - well, anything can be used in beer if you’re brave enough, but those are the two major players I know of - and without grapes, berries would be a fine analogue for wine.
I’d personally prefer if high-level farmers - say, the level after they’re able to be promoted to cook, so your second farmer - were able to make a compost heap. Once it’s set up, workers would move rotten food into it, and when the food rots away and disappears naturally it creates compost in the heap based on crop growing time. Carrots and turnips create one unit, corn would create three. If there’s other uses for that specific rotten item hearthlings can just remove it from the compost heap for their own purposes before it disappears.
Farmers can then take compost from the heap to fertilize probably 3 tiles of dirt (66 usable tiles in an 11x11 field = 22 units of compost for one full field; with backpacks one farmer can carry 8 units of compost = 3 farmers to fertilize a whole field without stopping to get more compost) when they plant seeds. All farmers can use it so you don’t get half-fertilized fields when only half your farmers are high enough level, but you need a farmer of sufficient level to allocate the heap and start the process.