nis, file permission and client question

[francisk at auston.com]

Hi ! nis users.
Appreciate if anyone can help to clear my doub for the following 
question.

1) file access permission

drwx rwx ---	ownerA	    groupA	1024 jul 15 17.41 holiday

member of groupA can read, delete and save the holiday file as 
another new name. Can member of groupA edit or make some 
changes then save it the same file name like the above (holiday) 

2) NIS gui
I have setup my nis server and client in text mode. My server is Red 
Hat 8 and client is Red Hat 7.2. Now I want my client to be in gui 
(graphical login screen mode). How can I do this ? Can I keep the 
nis server is text mode but the client in gui (graphical mode) ?

3) Netgroup
Can anyone explain to me about netgroup. I am trying to understand 
how to use netgroup to manage my user groups

Thanks and appreciate your help

francis