1) yes, the hwbot engine supports 1 team, multiple fora since rev2.0. However, a good interface for merging teams is missing and but has been coded already for v2.1. So if you can wait a few weeks until v2.1, i'd be easier.
2) no. by merging to one team you all become ... one team. The only difference between a normal team is that your bots can scan multiple forums, but you will be presented as one team.
To see how it looks, check out H.O.T.:
http://www.hwbot.org/searchTeams.do?teamId=1632&name=H.O.T.+%28Hellas+O%2FC+Team%29
If really wanted, I could add functionality to search or list scores by 'sub' team, based on the forum that has been scanned.