I see several other boards that host community discussions and I
wanted to know can we start doing this?
The chatroom is open to everybody for a reason. Any user (>=20 rep) can go ahead can initiate such an event and organize it. Any room owner can create it, however, its best if the event is created by a Moderator. The difference being that events created by Moderators get some automated publicity by appearing on the Community Bulletin an hour before the event starts.
Are we allowed to do this in beta?
Yes.
What could be some topics to host?
If chat is not very active, then general discussions would be a good way to kick off things. Alternatively, there could be themed or targeted discussions too.
Can we do this on a certain day at a certain time?
Yes. Time and date have to be decided before the event is/can-be created.