I would definitely make sure the date of the event is in the topic title, as previously noted in another topic. That is, by far, one of the most relevant things about an event topic – when is it?
(followed closely by “where is it”, which could be relevant, depending on if the audience is global or local.)
The topic close date should probably be sometime after the event to give people time to discuss it afterwards.
As for Google calendar syncing, that’d be plugin territory.