HFS+ is the current standard, better known as HFS Extended. Journaled HFS+ allows the drive to better maintain data integrity in case of power loss. Spotlight incurs a larger performance hit that journaling does, and neither have too great of a penalty for minor work. So you want HFS+ Journaled for your FireWire-connected external drive.
How the hell did you manage to read my mind-- oh. Wait.
RAID systems can be faster. It depends on the disks, what level array, etc. Example: a RAID 1 array with 4200 disks isn't going to be as fast as your 7200 drive. But your 7200 drive isn't going to cut it when it comes to a RAID 0 array and 15k discs. Oooooohhh yeah!