Having an instant +10% MP isn't a bad idea but I would rather not have it tied to lightspeed. MP regen mechanics encourage you to pop abilities as often as cooldown allows, when Lightspeed is best served as something you pop when most needed.

Moving Gravity to a level lower than 52 is the best change on this list. Then maybe I can run 50 roulette on AST again. Giving Combust II the free Bane treatment that Aero III enjoys is also not a bad idea.

Making Time Dilation an AoE is unnecessary, as that's the entire purpose of Celestial Opposition's existence. Additionally you are not supposed to be able to dilate yourself, though I still haven't a clue why this is.

I won't comment on card tweaks because my problems with AST are largely its mana management in raids, or lack thereof.