My game world has an extensive history worked out for both Mountain Dwarves and and Hill Dwarves and why they hate each other, but I've avoided doing any real work on them as 'races' or 'classes'.
I like your version of the Dwarves. I don't mind the 'whirling dervish' so much, so I'd probably just add some of your stuff on top of whats already written in the beta. In general, I'm waiting to see what the final version of the non-humans look like before doing any extensive work in this area. I've been too busy with Deities, Patrons, and spells to worry about it.
I also like the idea of making the spellburn cost more after the casting, I may consider adopting this rule...