Your stats are pretty solid for where you are at. Enchants, talent build etc nothing to ***** about.
A rough guide to mp5 vs crit is 8 mp5 = 1% crit. That is very rough estimation though since the actual numbers are different depending on Holy light or Flash of Light. Generally at a t5 level you want 100-110-with 24%+ crit. You are a little mp5 heavy but not all that bad. In fact you`re just right for T5, at least better geared than I was when I entered it thanks to badge loot and vindicator neck.
As for a hard cap on MP5 I don`t think there is one, hell I am 250+ mp5 while casting when raid buffed now. As always I recommend balance, Spell crit and Mp5 both give you mana back end of the day, spell crit favours short sharp fights, mp5 long ones but over all with 26% holy crit (base) and 156 mp5 while casting (unbuffed) I still copious amounts of mana back from both. If you look at a Pally that stacks just MP5 or just Crit they might get more mana back from that one but when you look at both together, they come out behind. So balance, look at gear look at gems, look at trinket.
As for consumables I would recommend
Elixir of Healing Power and
Elixir of Major Mageblood, though if you find Ancient Lichen is a pain in the *** to purchase you can always use Draenic Wisdom. Food is Sporefish, I also keep a stack of Golden Fishsticks on me (if only cause I fish my own and I catch them in the process)