I am well aware of how に works compared to で and how to use it in various situations. I still have trouble with a few uses that keep popping up, as they don't seem to gel with my current understanding.
For example それは体に悪いです
I see に as a particle that shows 2 things,
A particle that denotes movement form larger area to settle in somewhere specific. It is used with verbs like 住む 勤める and 乗る for this reason.
A particle that effectively turns the noun or quasi adjective into an adverbial phrase. Used with 静かにしてください ハンバーガーにします etc to show the way you will "do" for want of a better word. It also is used in passive phrases to show that it was by someone else's motions that something happened, like "田中さんにビールが飲まれた"
So my question is, how do I understand phrases like 体にいいです or 会社に行くのにバスと電車を使っている Is that a third usage meaning "for"?
BONUS QUESTION:Are there any other usages of に I should look out for?