1) 908 is my main attack spell, the splash can stun as well for crowd control. That being said I have not found a reason to Attune to an element, it seems more an RP choice than a hunting benefit.
2) 502 can be a nice setup if the critter stuns but basically mages bolt, the other CS spells are either mana intensive or not as damaging for the cost. 519 was down-tweaked but 917 hits harder than in the past, still a lot of mana until near cap. As for 409/415 - feh, 3 or 4 casts of 903/904 seem more effective. 901 actually gives the biggest bang for the mana buck if you have the time the cast it repeatedly without rapid fire.
"You're well beyond training for a reason."...Gelston