This is my advice.
Use Battleforums as or in the clan name. good advertisement. Don't call yourself a clan though, thats juvenile. Team is more professional and sounds more respectable. Clan sounds like the 12 yearolds getting together to play money maps or beat 'nubs'.
Should use the same name and tag for Starcraft II and Diablo III. So you are considered part of the tea/clan regardless of names (and easier to switch between games).
Break team into squads, where each squad represent a certain segment of the style of play. Example: SCII would have a squad based on doing AT games, and another doing Competitive play, and another doing casual play etc. Diablo III would be mroe PVE, PVP and other such team based stuff.
Why I suggest this is it segments command so one person going inactive doesn't mean the whole thing topples. It would work military strucutre, Squad members go to squad leaders, go to the next person up and so on.
It's worked in two of the SCII teams I was on, and it worked really well.
my 2 cents.