2007 A8 - one problem or many?
 

I bought a used A8L last weekend. Car runs great but there are a few problems and I would like to know if they could be related (for example through a faulty power supply or relay).

Problem 1: Sirius is constantly LINKING. Signal some on for a few seconds and disappears for 1 hour... Independent of cloud coverage, tress, etc.
Problem 2: Parking sensors don't work consistently. Often, the light under the P in dash blinks when the car is in reverse.
Problem 3: Rear camera works intermittently. When R is engaged, the camera turns on or not, stay on when driving forward or quickly shuts off...

Any help appreciated.