1) Set up a decent sized LCD/plasma screen perhaps at 45 deg. to the main stage, so its to one side, but can be seen by audience and obliquely by speaker. fed by a laptop (Mac or Windows) that has a good (Nvidia?) GPU so SL looks good on it. Set up for ULTRA visuals. Add an anti-idle device to the avatar logged in, so its not logged out for inactivity. Set camera so all the Venue is in view. Just leave it feeding the screen. No attention necessary all day after that.
2a) Nominate a person/avatar to act as relay for questions between SL audience in chat mode or IM to nominated avatar to the RL venue. Make sure the chairperson knows that this person is representing the whole virtual audience when they ask a question, and can state it as such, and recognize the person as representing many others.
2b) As an alternative (which we are now starting to prefer as it allows for multiple modalities, some people in SL and some on other virtual participant mechanism, and allows for the envisaged participation via mobile phones, iPods, etc), monitor a Twitter feed on a nominated search tag (e.g. #openvce) and take questions and issues from virtual participants on that. AV people can monitor the same channel to see if there are issues for their feeds to the virtual participants too. Use your favourite Twitter client on any platform, even you iPhone, iPod or cell phone... or just open this page which shows last 6 messages with tag #openvce refreshed very 30 seconds.http://openvce.net/custom/twitter-feed-json-openvce.html