Hello, please bear with some silly questions 
My class has just got a pair of eMacs with OS X 10.2.8. We're supposed to make a "survival kit" on Mac OS X, and since no-one there knows Mac, I have a few questions.
1. You boot in to safemode by holding Shift just after the startup tone sounds, right? What other boot options are there? How do you boot in to Darwin?
2. Related to 1; is there anything akin to the BIOS Setup of a PC?
3. When troubleshooting a Mac, is there any reason to boot in to Darwin? (Is there any critical troubleshooting you might have to do in Darwin because you can't in the shell?)
4. Antivirus programs; I heard there is no reason getting them unless you work with MS Office docs?
5. Is the built-in firewall good enough for home users? Any difference here from 10.2.8 to 10.3 and on?
6. Defrag. I heard somewhere that OS X is supposed to do some defragmenting as you go? Are there any free defrag programs worth using?
Thanks for any help!

My class has just got a pair of eMacs with OS X 10.2.8. We're supposed to make a "survival kit" on Mac OS X, and since no-one there knows Mac, I have a few questions.
1. You boot in to safemode by holding Shift just after the startup tone sounds, right? What other boot options are there? How do you boot in to Darwin?
2. Related to 1; is there anything akin to the BIOS Setup of a PC?
3. When troubleshooting a Mac, is there any reason to boot in to Darwin? (Is there any critical troubleshooting you might have to do in Darwin because you can't in the shell?)
4. Antivirus programs; I heard there is no reason getting them unless you work with MS Office docs?
5. Is the built-in firewall good enough for home users? Any difference here from 10.2.8 to 10.3 and on?
6. Defrag. I heard somewhere that OS X is supposed to do some defragmenting as you go? Are there any free defrag programs worth using?
Thanks for any help!