1) Okay, moved BAB down to 3/4. You guys make a convincing argument.
2) Yeah, I'll admit that your Purple Worm inspired quite a few things on the Remorhaz, since they are somewhat similar in concept.I did move Burrow down to 3rd level, trading it with Ambush. I figure that by that level other classes are getting closer to things that make a soft-surface burrowing ability less useful. On the other hand, I think I can move it back still further if I need to. I've got an idea or two in my head that aren't quite developed yet.Lurker should help fix this.
3) Hopefully the changes to Heat will help clarify it a lot. It had some really dumb issues that I really shouldn't have let through on the first post, but I'm a terrible self-editor. Either way, I gave it uses and consequences somewhat like a barbarian's Rage, but I'm still not sure how well its balanced. As for it being a passive ability... Its the Remorhaz's signature ability. Hopefully having it be a few times/day will help it be a battle form/dramatic fight ability, but its going to be hard to drift away from passiveness while still keeping the flavor of the original. Ideas are welcome.
4) Sorry for cribbing Flexible, I probably should've asked about that first. I'll get rid of it if you would rather I not use it. On the other hand, it really fits what I'm going for with this class: Melee battlefield control.
5) I lowered the range and damage of the earth/rock use of Pyroclastic Belch, let me know if that works for you. The goal is to make each use approximately equal, while giving a creature without limbs a ranged attack option. I'm not sure if this is overdone for that, but it seemed like it might be alright to deal with flying opponents occasionally.
6) I'll admit that Firey Surge was really messed up. The image in my head looked like Castigating Strike + Explosive Fireball, so I stole the mechanics from both and mashed them together. Not exactly smart or balanced. Either way, I've modified it, so that it does less damage(equal to Heat, so 4d6 instead of 7) got rid of the knocked prone part, and played with the radius to be a little less silly. I also added the use/day that I forgot on the first iteration. Hopefully, that will make the Remorhaz's alpha strike a bit less broken, and a bit more playable.
Sorry for not getting back to this very quickly. Hopefully I should be able to really work on this and get back to critiquing monsters after the holiday season.