Group 1:  How realistic is this?  What time committment is involved?  Leverage eachother's strengths across hubs.

Group 2:  Everything!  You have different target audiences - look at demo and determine the best way to reach the audience.  You need to expand the community of interest beyond usual suspects.

Group 3:  All of the above - email, face to face meetings, social media - depending on the context.

Group 4:  It is all of these tactics - email, face to face meetings, social media - online and offline people have different touch points.

Group 5:  It depends on the message and your audience.

Group 6:  Face to face meetings and email, IGLOO social network.

Group 7:  All of these - email, face to face meetings, social media - and events.