3.2 Random switch and engine light

[Radraddad]

I have been slowly going through the car and finding lots of things that need to be repaired/replaced I am hoping you guys can explain the little switch that looks like it's missing a housing with green wire attached in the photo.

Also, the clip above the hanging switch is unknown to me, and I am wondering if anyone might know what it does.

A couple of other questions since I might have the opportunity to chat with some.

Wondering about the brake booster that is sealed with electrical tape. Is this an easy fix if I purchase the part? The fitting is like $150, and Im not sure if it's going to be a pain to reach the line.

The Engine light that mounts to the hood is not getting any power, and I have no clue where the wires lead to. The fuses on the panel are all good to go, so I'm unsure where to look.

Lastly, I think I overfilled my AC with freon, and now my AC blows hot air. Is this fixable, does the excess freon have a way of escaping? There is green fluid on the heat exchanger fitted against the hood lid. Not sure if I have damaged it or not.

Thanks in advance, you guys are always super helpful.