The AC bonus is untyped. As is the speed bonus.

Snap Kick has a +6 base attack bonus minimum, so Heidigger wasn't able to get it until level 9. Regardless, his Wis and Dex are both pretty good, so he tends to hit most of the time. In Tomb of Horrors, it especially isn't an issue because most of the opponents have low-ish AC for their CR.

I take a... fairly radical approach to feats. I've rewritten a couple hundred of the sub-optimal feats to balance better and scale with increasing level. One of these days I'm going to burn the Book of Feats and the Book of Classes to pdf so I can show what I'm talking about instead of just making vague references. Specifically, in this setting Mobility is part of Dodge, while Bounding Assault and Rapid Blitz are part of Spring Attack, unlocking as the character levels up and achieves the appropriate base attack minimums. This means that Heidigger need invest only two feats to get the benefits of Dodge, Mobility, Spring Attack, Bounding Assault, and Rapid Blitz, although he won't get iteratives with his spring attack for many more levels yet. IMO, this is a more appropriate cost for the benefits provided by the feat chain.

Quivering Palm is delivered as part of a normal melee attack. Its effect is in addition to the damage the attack would normally deal. It can be delivered whenever the monk is making an attack, even on an out-of-turn AoO (although the death trigger can only be performed on the monk's turn, since it's a free action).

An SR-boosting feat is a good idea. I'm planning to overhaul the OP later this month and do a comprehensive edit to improve the presentation and spruce up the higher-level features a bit. I'll include that feat when I make my edit.