2003 ZTW, Numerous issues

I'm in the process of trying to resolve some problems with this vehicle:
-Serpentine belt chatter when A/C is on. (constant problem for years, replacing tensioner didn't work)
-Collapsed Motor mounts (4th time!)
-Rear wheel bearings (3rd time)

I'm told the belt noise and motor mount issues MIGHT be resolved by using genuine factory parts, which is what I always thought were being used. I'm fine with buying my own parts and giving them to the mechanic for install, but I would like some feedback on whether or not people think that certain parts are better than others at fixing these particular problems, and where I should order them. I'd rather do so online if possible.

Thanks.