Path of Belial/Fierna: I'm assuming you mean each round they deal/take at least their character level in damage, they gain the benefits you listed, not each round they deal or take exactly their character level in damage.

Giving them permanent Sadism/Masochism is really, really powerful. Those spells, especially when you combine them, get brokenly powerful fast. Perhaps simply give them the appropriate spell as a SLA once or twice a day instead, or make it so that they cannot benefit from the other spell (Fierna's acolytes can only benefit from Masochism, while Belial's can only benefit from Sadism) to tone down the power a bit. I love the flavor of this ability, though; it fits perfectly.

For the Sudden Metamagic abilities you give them, you want it to only be 1/day, like the other Sudden Metamagic feats, right?

I so want to play this class, and soon!