Same process. Download the rom, transfer it to the root of your sd card, reboot to recovery, wipe data/factory reset, wipe davlik-cache, flash the rom, reboot.
yes, the nandroid is the backup/restore process. I use Amon RA and it is called that in recovery. Clockwork I believe just uses the backup/restore option.
Again, just make sure you make a backup before you make any changes to your phone. If you run out of room on your card, you can transfer them to your pc for safe keeping and delete them(leave at least one known working backup) from your sdcard.