1). Idea is, researching how to better patch someone up requires a "learning dummy" (slave) booze (to properly incapacitate someone to practice cutting on) and medical supplies (to be wasted figuring out how they work best. That's actually the whole point, making research that's more resource intensive without the whole "is there some item I didn't craft somewhere" syndrome. It would streamline say, badges for bounty hunting in piratez, and allow more compact dealing with things. Technically we can do this now, but it has some downsides. 1,it requires crafting, which can end up easily lost, 2, it requires free crafting space, and 3,it makes researching said thing a 2 step process of craft and research. Its a bit wonky all around, I'm sure you can admit.
2. ui, a good question... I was thinking perhaps select research with requirements, could be a different color, and have a button inside the research labeled "required supplies", or if there's room, put em down. I figure tech tree viewer could display needed items too, and you could list items you are tech ready for, but lack supplies towards the bottom of the research list. ADMITABLY, ui is the biggest issue here, but I don't think its insurmountable. Even just a tag for like *r* on research, to show requirements, looking at tech tree viewer, and showing an error if attempting research without would work, I think.
3: depends on the mod. Xcf currently has no manufacturing for the first year. I realize you address xcf bellow, but it would also prevent losing core research items in a mess of manufacturing items. Currently a lot of care must be taken so these items are pointed out as "hey, research this dummy" so people don't end up stuck. It would make things less obtuse afterwards.
4: suppose I have nothing for this that isn't a rehash. Just feels like it could be a quality of life improvement for modders and players in some situations.