re:Mage Hunter
This PrC seems a bit overpowered, and maybe a little ill-focused, too.
At first blush, you get all good saves, good BAB, d10hp and 4 skill points a level. That's an awful lot without adding any other abilities. Then there's some very potent damage bonuses from 2nd onwards, (weak) spell resistance at 1st level, and Divine Grace at 3rd level.
It's a bit too much, if you ask me. (And you did

)
There's also very little to help in attacking spellcasters, other than BAB and the damage bonuses. Specifically, there's no mobility powers and no means to overcome or remove magical protections.
I'd suggest dropping the BAB to the second tier, and maybe lowering the HD. This makes the PrC fairly similar to the Monk, and seeing as it's going to have a lot of magical abilities, that seems a good point of comparison.
I recommend dropping the added damage and increased critical range abilities. In their place, try adding:
A power that creates a targetted
Dispel Magic effect with each hit. Make the caster level equal to class level, and grant the ability at 5th. (Optionally, give a +2 bonus to this at 10th level.)
Some sort of travel power. Either something like the Epic Feat, Spell Stowaway, or just
Dimension Door.
A power that limits the effectiveness of defensive magic. Good ways to present this might be by giving a bonus to attack equal to the lesser of the Mage Hunter's class level and the targets Deflection/Luck bonus. Alternatively, you could just give a scaling bonus to attacks against spellcasters. Either of these, combined with the 2nd tier BAB, would bring forth the Mage Hunter's specialisation.
Mettle (from DoF) and/or Evasion.