What can I do? The pads and rotors gave just been done.

Last year my vans heat would come on when in cool position. Almost like it was stuck. Turn off fan and car then it would work again. Air conditioning worked very well.
This summer, air conditioner would not work and there was a ringing sound, now there is a louder noise when all front fans are on. None when only the back fan runs.

Is my air condition shot.

How big a problem is this to fix

For the past three days, this charging system failure goes on. I was wondering if I drive around too much, it will die on me on the highway. Do I need a new battery? And last summer i got a new alternator put in. And everytime i past a puddle of water my driving wheel is hard to turn.

My gas Gauge keeps dropping to empty even when full