[colts6900]

i am pretty far along in the game, i have just gotten the warp stone, and i have also had my characters "upgraded" to the alternate class, knight, red wizard, master, and ninja are what i have all lvl 40+ and each know some kind of magic except the master. i need to know a few things..
1. where do i go to find the 3rd and 4th crystal?
2. what does the warp stone do?
3. in the city Gaia does the little barrel submarine actually work as a machine like the ship or airship?
4. finally does the master get any other weapons except iron nunchakus and a crosier?

please reply, i would greatly appreciate it!