I wouldnt suggest to use the automated CC at all as an mage, the cr itself is optimised to play with hotkeys.
e.g. if you press "Poly Healer" hotkey and once the cr starts to poly the enemies healer, you can press "RoF Healer" and it will spam RoF asap if you get interrupted on poly.
For all 3 specs you should do as much as possible with our predefined hotkeys to get high rating, fire imo works very well if you control the burst hotkey by yourself and disable DragonsBreath outside of Burst. But I'm always happy to receive suggestions.
Arcane does support PoM, you simply have to activate it by yourself. But yes a "PoM Poly Healer" toggle would probably worth it.
Imo Mage is our strongest caster cr and is my most played class after Warrior.