Grouper Users - Open Discussion List

I am new to Grouper and am trying to understand some of its features. I have 
been unable to find answers to a few things in the doc, examples and lists so 
far.

1. Is it possible to assign group permissions (e.g. ADMIN, UPDATE, READ, 
etc.) to another group so that everyone in the designated group receives 
those permissions dynamically?

2. When using the group permission "OPTIN", it seems that you have to define 
in advance all of the subjects that will be allowed to opt in because the 
permission is assigned to a subject. Is it possible to let any subject opt in 
to a group without having to specify the subjects in advance?

3. I have seen "groupLookupName" in some v1.4 web services code samples. What 
is it used for?

Thank you.
Paul Gazda