Is it ok if my right lip, chin, & gums are still numb 3 weeks after wisdom teeth surgery?

Paresthesia. Your paresthesia could be related to nerve damage during the procedure, some inflammation and swelling still present, or an infection not completely resolved. The longer the paresthesia lasts, the less the chance of full recovery. The good news is that it's still relatively early in the time range that would allow full recovery. This should be monitored very closely. See comment->.
Yes and no. This is not an uncommon side affect of the surgery. In most cases full feeling comes back but it can months. It depends on how difficult the extraction was.
Nerve injury? It is possible, because wisdom teeth are often very close to the lower jaw nerve, that the nerve was inadvertently injured when the tooth was extracted. If the tingling has stopped and there is still numbness this could require surgical repair of the nerve. I would contact your oral surgeon so he can determine whether or not the nerve will heal by itself.