[silverstone_ttlz4]

Few brake-related questions I was hoping someone could chime in about:

1. So it's one sensor per axel? Any experience with aftermarket sensors? I saw some on Tirerack and am intrigued because they look to be 1/3 the price.

2. What is a fair price to pay for a dealer or private shop to charge to install new brake pads and sensors on the front and rear?

3. If I'm not having any issues like squealing or vibrations etc., can I assume the rotors are still a safe thickness? The car is an 09 and has 50K. I'm trying to keep costs down and don't want to replace them if it's unnecessary.

4. If the computer is saying I need new rear pads (can't recall which it's saying need to be replaced), should I just replace all four corners?

Thanks in advance