Mfslgoldcd, you were not alone in falling for that marketing gimic. The ones I used were both the pre-Monster red ones and then the Monster multi-colored ones. I had about 30 of these on cds and removed all of them about 8 years ago. I did it because I thought the glue would somehow chemically react to the label/protective layer and cause the reflective layer to become pitted or dull.
The answer to your second question is NO...but... Having them on will not add stress to motor mechanism, if they were put on right in the first place. However, they will probably not play in today's car cd players due to the openning slit size on the players.
Now to answer your first question. The rings can be removed but you need to be very careful, work slowly and be patient. Failure to do this will damage the label side and cause cd to be unplayable in the affected area.
cd burner - insurance measure
Hair blower, with low/medium/high heat settings
Lighter Fluid (Ronsonol)
First, burn a copy of all the cds you are going to work on. I wish they were readily available when I took on this project because I ruined four of my cds because of the poor quality of the protective coating underneath the label.
Next, with the cd on a regular jewel case cd tray insert and using the low temperature on the hair blower, start heating about 1/5 of the ring. With your finger nail, pick at the edge of the ring from the outside edge to see if it will lift off the label. DO NOT RUSH OR FORCE IT! Once it starts to come off start heating the ring in the direction you want to lift off next. Some will come off relatively easy and others will take longer. If you can't get the ring to start to lift then forget about it and move on to the others. Removed rings will leave a glue residue on the label.
Lastly, using a 100% cotton rag, squirt a little liter fluid on the rag and gentle remove the glue residue. Yes, some of the label ink may come off at this time but it doesn't appear to cause any damage to the protective coating underneath. As an added measure of protection you might want to put a little clear-coat car wax on the label side once you have removed the glue. I can't recall if I did it back then but part of my memory seems to point in that direction. All the cds that I removed the rings from, and were not destroyed, play fine and show no signs damage to the reflective layer.