Hello Fishermanjm!
There really is no need to defrag. Macs use HFS journaling which IMHO is very efficient than FAT32 and NTFS. I believe there is a utility you can download to defrag, but I have been running my G4 for almost 2 years and my MacBook Pro for 7 months and I haven't defraged them since I owned them. They are still really fast at reading and writing. Plus, I believe you have to pay for that utility.
The only piece of software you may use regularly is Disk Utility. If you ever notice applications acting a bit quirky or you computer acting sluggish, Go to your applications folder. Scroll down to Utilities and go into it. Open Disk Utility and select your Macintosh HD drive. (Make sure the First Aid tab is selected). Now click on repair disk permissions. After it has completed, restart your computer. That's really the best way clean files and fix corrupted preferences.
As far as restoring, I need some clarification. If you are talking about reinstalling the OS, it's pretty much like Windows except it's a bit easier to figure out what is what. Everything is well marked.
Let us know if you need further assistance!
Cheerio
Searay