SSH access to several users - jail ssh and limits

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Hello all,
I just installed CentOS 6.3 on a PC in our company.
PC should be used as a development server.

we have 6 developers in the company and each should have a user.
1. each user should have access only to his home directory.
2. all of the developers should have access to /var/www folder
3. all developers should have access to use svn and git
4. access git repositories should be by users
for examples user 1 + 3 can access repository called site1
users 2+4 can access repository called site2

can you refer me to guides / ways to do any of the following ?
or if some one can explain here ? at the moment im blank :)