When you setup Time Machine, it asks you to choose backup destination. You don't seem to be able to drag your boot drive into the list, but afp servers show up automatically. My bet is if the Finder can mount it and write to it, Time Machine can use it.

cron is a system tool which runs 'maintenance' scripts at scheduled times. It can be modified to include extra scripts and to change the times it runs. There is a shareware app which provides a GUI front end to it, I forget what its called.

If you want to learn the terminal or scripting, I would search over on the oreilly network. They print many Mac textbooks and have alot of useful stuff on their site. The Jaguar based terminal tutorial is still close enough to be of use in Tiger.

the 'man' command can be used with another command as its argument to display the maual for that command. This tells you what it does and how it should be used. Open Terminal and type: "man cd"
This will display the manual for the cd or change directory command. press q to get out of a manual page.