NIS and user management how to

Hi ! Linux user group
I have setup my nis server and client successfully with Redhat 8.
Presently my server is NT server. I would like to migrate all my users to
Linux NIS. I would like to know what is the best way to management
my users.

1) I have about 25 departments and 70 users. Members of each
department can only view and alter the files and folders in their
department. Also, I have a public folder where everybody can save,
copy or edit a file and directory there. What is the best way to do
this. Should I create each department in /etc/group then assign the
right permission.

2) I have read about the netgroup but not quite understand. Can
anyone tell me what it does ? I only have one nis domain and one
linux nis server. Should I use the netgroup to manageme my user or
just use the /etc/group (groupadd)

3) If I have two nisdomain is it advise to use the netgroup ?

4) Can I do without the netgroup to manage my users (create folder based on
dept name, public folder where everybody can access, and etc.)

Appreciate if you can help.

x2000koh