In fact, it is a good procedure to restate the question even when you know the answer. Then, depending on the setting, you might be able to redirect the question to the group to see if anyone knows the answer. This may be sufficient. If not, indicate that you do not know or are uncertain but will find out and report back. You do not need to appear as the repository of all know-ledge.
Students appreciate a straightforward, helpful attitude.
Sooner or later you may make a mistake and provide incorrect information on some issue. As soon as possible acknowledge that and provide the correct information. Getting Paid One administrative component of being a TA is ensuring you get paid. Human Resources arranges sessions for graduate students each term. Your departmental graduate secretary should post information about these sessions.