a web application request

So here’s what I want:

1. To be able to view my calendar (and sync it to my Zire 72’s calendar and iCal) online and edit it online as well.
2. At the same time, I want to be able to allow other people (people I freelance for) to put in requests for time that is viewable to me.
3. I want to be able to add tags to each scheduled event I have posted.
4. And when I confirm a request, it should send an e-mail to the person who requested it confirming the request.

I hope Google Calendar can do this, probably without the e-mail confirmations though. I checked through the MoMB site, but no luck.