A quick way to often speed up and make rules in the shop is to put a sign-up.
It can be very frustrating for you and your staff to keep answering questions. Often what you will find is common in-store questions can be answered quickly with a sign. It may give quite a relief from having to repeat the same answers over and over.
Not only that but it will save you a lot of time.
Here is a good site where you can make free, a professional looking sign, print it out and stick it on the wall.