Setting up a hierarchy of 4 groups in Centos 5.3

This is a newly installed Centos 5.3 and my questions have to do with setting up of users and groups to obtain desired functionality.   I would like to use the command line (bash) instead of the gui.
 
  There are 4 groups, novice, beginner, expert, guru;

Shared folder for each user:
 Each user has a shared folder with read access to others in his group.   But read access is also granted to members of higher groups.  So if a novice1 user has a shared folder, he would be able to write to it but all novice members and members of other groups would also be able to read that folder.  Similarly if guru1 had a shared folder, only other gurus would be able to read it.

 Common folder for each group:
Here all group members can read and write (to the group folder); So novice1 can read and write to this novice common folder as can novice2 etc.   expert1, guru1 and beginner1 can also read and write to the novice common folder.   The common folder for experts can be read and written to by all experts and gurus.

Is the way to set this up is to make gurus members of all 4 groups, experts members of 3 groups, beginners members of 2 groups and novices member of the novice group only?  Any other configurations to be made so that the desired behavior is obtained (read and write) when people use sftp to write and read files from various shared and common folders.   Ideally each users home dir would have links to these shared and common folders (the ones that they can at least read)
 
  I am guessing that symbolic links could be used so that all the relevant folders that users have access to appear under their home dir.