1) The idea is to create easy "google like" web calendar
(functions and look similiar to google calendar and http://calendar.digitalinterchange.com/index.asp ) with login page at first to get permissions.

2) Let me add/edit/delete an event(s) and let users to sign up for it. I need to set who can sign up for it guests or registered users, what information they need to provide (all set in admin, unlimited fields).

3) Let me create users that can have different permissions:
Guest - (R) Read only events, (R/W+)Read/Create/Edit/sunscribe to Events only, Subscriber (S)(just subscribe to events (let me set limited or unlimted date range)), and (A) Admins (RW permissions and creation of users, config settings).

4) Let me set what events or the whole days are public and what are private (require S, or R/W or A permissions). If the day is private or an event is private, do not open it,unless the user has a permission. If the event is private do not show it on the main calendar unless the user has a permission.

5) Let me set what kind of calendar month is shown, and if calendar browsing is allowed. Let me set what is shown on the screen when user subscribes to or views the event.

6) Let me import and export part or the whole calendar into and from Microsoft Outlook Calendar. Let me specify date ranges(CSV, ICS, PST and VCalendar file types). The users who signed up should be in Notes field for Outlook.

7) Let me see who signed up for an event (A only). Let me set if the who signed up for an event is public or private information. When an event is deleted, the who signed up should removed from the event. 7b) Let me delete signed up users from the event.

8) Different users login using http querry string.

9) Let me bulk edit or delete events based on dates range and individual selection of events.