Confusion about announcement boards

[Golden Tiger]

Ok, I want to do a few things.  Tell me if they are ok or not, and how to do them...

First, I want a group of people to access a special category (I know how to lock out that category for just that group).  If I make an announcement board in this category, will the group recieve announcement notifications from both announcement boards while all the other users (who cannot access this category) will continue to recieve notifications from just the one announcment board?

Second...  Who can post in an announcement board?  Everybody, the admin, moderators?  In one announcement board, I want only the admin to post, and in the other I want everybody to post.  So...  how do I do both?

What I want to do is this...  I want to have a normal forum, one announcement board to announce important news... then, on my board, I want a category that only a special group can access.  As the members of this group complete certain parts of a project (that we are doing) they will post a message into a second announcement board and all the members of the secret group will be informed of that user's progress...  I want a way to do this...  Any suggestions on how to go about doing this?

Thanks for any help you can give me!