1. There's nothing wrong with players answering questions from other players if they know of the topic in question. Answering questions and mini-modding are very different, which is what I believe you are concerned about. Mini-modding is when players act like staff, as in saying stuff like, "You'll be muted for that!" or saying they will distribute a staff-given punishment.
2. On the forums, no. But in-game, as stated above, it's acceptable for players to answer questions, given the information is correct.