Based on googling the problem, it seems that it's most likely the clutch bearing.

The question I have right now, is if the bike is safe to ride (i.e. Will I do more damage to it), or should I avoid riding it until I can do work on it myself or drop it off at the shop?

Thanks!
-Adam

 

If the bearing stops spinning then there goes the hub,replace it while it's still (hopefully) just a bad bearing.