I am using Time Machine to back up my stuff onto an external hard drive.
That's good, a lot of people don't do any sort of backup.
If for some reason I need to start all over and re-install Snow Leopard plus everything else, I'm confused as to the best way to do it.
There are three or four ways. One is a complete rebuild via the Snow Leopard install disk, the second is a restore from a TimeMachine drive and then there is a reverse from a bootable clone. Last is a Disk Image restore but that needs a boot disk for Disk Utility to work.
Two of the most popular and fastest to restore from is a TimeMachine or Bootable clone. Clone being the fastest and easiest of the two.
Do I boot from my Snow Leopard install disk and restore using my Time Machine backup?
Yes you can do that by holding c and booting off the Snow Leopard disk and then can perform a TM restore.
Or should I get SuperDuper or Carbon Copy Cloner to make a bootable backup?
Some people use both methods. Too backups are better than one.
Is there an advantage of one method over the other?
TimeMachine drives are not 'hold the option key bootable', clones are.
TimeMachine keeps various states of your OS and files so you can restore back in time a little bit depending how much drive space you have. This takes up more drive space to do this.
A clone is just a clone of a exact state when the clone was made or updated. So it's the same size as what you cloned.
A clone has the advantage of booting the computer if the internal boot drive is dead and/or the Superdrive or disks can't be used. One can be up on a clone in the time it takes to boot off of it. So there is little downtime, it's great for misison critical use.
A TM drive requires the boot drive (and internal Superdrive if broken) to be replaced if it's failed before the comptuer can be used again.
TM has the advantage of restoring previous or accidentally deleted files, a clone once updated, the deleted files are gone.
My understanding is that I would NOT be able to use the same external drive that I'm using for Time Machine to make the bootable backup, as SuperDuper and Carbon Copy Cloner erase everything. Is this true?
You shouldn't as both your hardware backup eggs are in one basket/machine, drop the drive walking over to your hosed boot drive and your done for as you just lost two backups in one accident.
If so, will I need to get a separate external drive for the clone?
You should, drives are inexpensive and fail often, data costs plenty more so doubling up is vital.
I should state that having a bootable clone is likely vital on iMac's due to the huge cost of opening up the device to replace the hard drive.
Apple has placed proprietary software on all new iMac's and thus less expensive third party companies (or skilled users) can't replace the hard drive anymore.
So your left dragging the machine into a Apple Store where the quoted price may make you consider cutting your losses and buying a new machine.
So with a bootable clone. you can just keep going as long as you can keep making clones.
Many thanks for the time and trouble you took to submit your detailed replies. It is because of people like you that these forums work. I am going to get an additional external hard drive, and I will download SuperDuper, in addition to continuing my Time Machine backups.
Everyone knows how life works: if you back up, you'll never need it. If you don't back up, something disastrous will happen. So I will continue backing up!