If you do a:
man syslog you will get a lot of your answers there.
If you don't have the man pages loaded with your OS you can go to http://www.die.net
and type in syslog it will show you the man page.
Not sure what Linux version you loaded but RH / Fedora uses /etc/logrotate.conf to determine how often to rotate all system logs.
Another tool for use with logs is syslog-ng. It is open source and works well.