inside wear on just 1 tire. reason?
 

The inner side of my right rear tire is more worn out than the opposite side. What would be the first thing I should get check? Alignment? Can it also be a bearing problem? Thanks

The alignment spec for these cars calls for quite a bit of negtive camber, which wears out the insides of the rears more quickly than the outsides. If its just one side, I'd start with looking at alignment.

A shop that knows what they are doing can decrease the camber to the minimum of the spec range to avoid the wear issues, but the handling may suffer.

+1 on alignment.
It's normal to wear the inside edges harder than the rest of the tire, but both rears should be about equal. My guess is that your RR has a bit of toe in.

Going with the NASCAR setup, eh?

Seriously, previous answers are right on the money. Your RR likely has more negative camber (not toe in) than the LR.

Would inside wear(nearly bald) create a "womp womp" sound that is speed dependent and not rpm dependent as well?

Yes. Any tire or wheel anomaly can cause speed-relative handling issues.