1) I hate it when nurses turf a patient question off to another discipline. Interestingly, so does NCLEX, and there's a good reason for that. The patient probably wouldn't be asking if his physician had done a better job of explaining, or if he hadn't been too anxious to take all of it in when the physician did explain. NCLEX wants to know what the nurse will do, not what someone else will do...and assumes that as a nurse you WILL do something useful and therapeutic for your patient. So, using the time-honored response that is rewarded by NCLEX for a good reason, your response should be, "What did your physician tell you about this already?"
2) Then you have the opportunity to clear up any holes in your patient's knowledge, like what a prep will involve (another thing NCLEX tests you on, and with more good reason), dietary or other precautions involved with a plan of care, what usual pre- and postop care involves (if surgery is in the medical plan of care), or whatever else is involved.
3) NOW you have an excellent opportunity to teach the patient to write things down "for next time, and when you go into the office." You do this after you have had the above conversation because now the patient realizes you know what you're talking about, realizes that you are his advocate, and trusts your recommendation. It will also be there when you go in the next day and say, "Did you think of anything else you needed to ask?"
4) Last, you document all this and tell the physician that his patient has concerns and questions about X, y, and z, and you have told him thus-and-such but he needs to hear it from his physician too. Often docs don't realize that they aren't being very clear about their instructions or explanations to patients (imagine that!) and this might help the doc amend his style.
5) Totally not a HIPAA issue unless you are saying something like, "Mrs. Smith, your roommate, had the same surgery and ..." Patient teaching as outlined above is never a HIPAA issue; it is a prime nursing responsibility to assess patient knowledge and do health teaching about care and recovery.