People do have to create an account, so it make take them a little longer.
Also some people might not notice the e-mail invitation at first. I'd
recommend to continue to bring it up in person and send an e-mail from your
e-mail reminding them about the invitation.
Your pages section is like a web-page, it's a place to put Frequently used
information.
Here's the basic guide
http://groups.google.com/group/Google-Groups-Guide?hl=en
Here's how to attach documents
Under Files choose upload files button.... then hit the browse button,
locate it on your computer and the next thing you know it's uploaded