Need advice on group calendar plugin (which to use)

Hi, I’m not a programmer but am fairly handy with wordpress and some html code. That said, I’m looking for a calendar plugin/app for my site. IO need to be able to do the following:

1) I have a specific group of people whom I want to allow to post events to the group calendar. Such that all users can see which members of the group are doing what things on what days. Obviously sometimes there will overlap (multiple members will have events on the same day) which is the idea of the group site. BUT someone looking at the overall calendar should be able to see all events from all members including the days in which there are multiple events occurring.
2) each of the members is authorized by me and must have their own profile that they can maintain/change their theme etc.. to customize for their look as they wish.
3) each of the members should be able to share their calendar on their own website, NOT the group calendar but rather their own individual calendar so that THEIR members can view only their events etc.

So this maybe more than a simple calendar app/plugin I dont know but would love some feedback and advice on the topic.. thanks

As well, I’m willing to pay for a commercial/upgraded version of a calendar app but it has to be affordable as this is a non profit..

thanks

Chuck