I have a web server (Ubuntu 12.04 LTS if needed) multiple people use with Apache, PHP5, and MySQL installed. All users have access to SSH. All users home directory's are /home/USER I was wondering:

1. What usergroup should users be in; or should they have their own usergroups()?
2. What user and group should Apache run under?
3. What file permissions should the users /home/USER/public_html and /home/USER directory's be, as well as subsequent files (including such PHP files w/ sensitive information such as DB passwords)

Thanks :)