Rays build is a good 1 to follow but I do what Hodges does. I max dura/BL then add 1 point to my dmg spells.
As for maxing Fireball. It all depends on ur playing style. Since mystics have AOEs/Heals/Single Target Fireballs usefulness relies solely on how u play that class. I have my fireball at 5 only since I rarely use it in PvP. My style is all about points over kills so I heal & AOE mostly.
I think, no matter what... mystics and forsakers will always cap...