Two API questions

I'm looking to be able to do three things that don't seem to be supported via
the API right now. First, I'd  like to be able to set the group to which an 
event
belongs when it is created (or via a modification after it is created). 
Secondly,
I'd like to be able to have the ability to set/unset the "going" attribute for a
user for a particular event. Finally, I'd like to be able to find all of the
members of a group given its ID.

Is there a way to accomplish any of these things with the current API? If not,
will these be supported relatively soon?

Oh, and one more question - do you guys have any plans to support watches
in the future? I'd like to be  able to get a notification at an external URI 
when
a user creates or modifies an event.

Thanks!
Joe