When the CX-7's headlights are turned on, there's a buzzing sound, like "zzzz." What could be causing this?

Hey guys, I want to ask about something. When I'm driving between 70 to 80 km/h, I feel the whole car shaking. What's going on?

The air conditioning isn't cooling. I checked the pipes and found no leaks. However, after adding refrigerant, it was gone in less than two months. For an 11-year-old imported Mazda CX-7, what usually causes this issue?

When driving over 120 km/h, the steering wheel and accelerator cause numbness in my hands and feet due to vibrations. Even slight unevenness on the highway results in rhythmic vibrations, making my hands and feet feel numb.

What could cause a sudden jolt in the Mazda CX-7 transmission at a speed of 100 km/h?