Reverse click
#4
It's a visual inspection. Get the car in the air and look at both. If they have cracks, they're done and should be replaced. There is one at each end of the driveshaft, and they are normal wear parts.
#6
There are three bolts that locate the third member in the chassis. Make sure they are torqued and not stripped. The two rear bolts go into the aluminum diff cover. Mine had been over tightened pulling the threads causing a "click" every time going into reverse.