Access Control for CiviCRM 4.5.2 on WordPress 4.0

[mieuxvivre]

I have about 2000 contacts split up into 8 different groups.  I have learned how to give access to the contacts in 1 of the groups to the group leader but I would need to further customize access control and I'm not sure how to do it. The group leader has access to CiviEvent and CiviContribute but I would like to limit him to only view certain campaigns and certain events. Also can I make it so we can only see his group when accessing CiviMail? How can I accomplish these 3 things? Please give me detailed instructions. Thanks!