iCal - secretary and sharing - HELP!

Hi There

I've been searching for some answers to some questions and cannot get any answers! Any help, hugely appreciated.

I have multiple calendars on my iCal - one for work, one for personal, one for special days, etc. I work in an office where we have both PC and Mac users. I would like to have the ability for an assistant to be able to:

Access my work calander (but not the details), and be able to schdule appointments in my calender too - which will be updated on all my devices via icloud. Is this possible? It would save me huge amounts of time and streamline my life!

Any help/comments/advice welcome.

Thank you