For [1, 4] I think it would need to rewrite most of the contents like you said which make me think that make a new game would be easier lol. (But it interesting btw)
For [2], I think we must use shield item to make 'defend' function be more functional. Anyway, I do not use this function much since I use Razit's spear (and also body) then throw sleeping mist to prevent enemies from attacking.
For [3, 7] I think it really interesting. But like I said, it would need to rewrite most of the contents and these functions would make this game be more like dating sims lol.
For [6] If we have this function, I think it must be more functions that would be updated and changed, like some materials/fruits/herbs can harvest in some season or some weather.