Hello,
to 1.) Yes you can have multiple organizers (in frontend and backend with different user rights etc.) And yes in the frontend the events are compartmentalized.
2.) What do you mean with search capabilities? We have a Joomla search plugin and addtionally a component intern search directly from the event overview (search is possible for almost all fields).
Yes you can display events by category, displaying by location is planed for the next version - but you can always search bye for these attributes.
3.) Facebook and Google+ Sharing, Google Calendar will follow soon.
Best regards,
Yves Hoppe