Chris ... I haven't done any "Carolina" rig fishing, but I have done a WHOLE BUNCH of "Texas" rig fishing Thumbs Up
I haven't found it necessary to add a colored bead to a Texas rigged plastic critter ... but, I have used a "rattler" inserted into plastic craws, with great success.
The swivel is there to stop your weight from coming in contact with the hook/bait, so as to allow the plastic bait to "swim" or "float up" above the bottom. Carolina rigs are meant to be "dragged" along the bottom, whereas the Texas rigs are meant to be more versatile .... dragged, hopped, etc. Texas rigs are efficient in shallow to moderate depths, while the Carolina rig is primarily a deep water setup. Texas rigs are better around cover, and sloping rocky banks .... Carolina rigs are better on fairly coverless bottoms.
... cp