Whether you go for full haste, full mastery, or mix haste/mastery is personal preference. They're all good in their own way.
Full haste would be better for multitarget fights, but at high haste levels this build becomes really annoying (imo, akraen seems to love it) because you'll be below gcd most of the time)
Full mastery is generally better for single target fights.
Haste/mastery mix is in between which is the build I'm using now. Atleast 12684 haste, rest on mastery > haste. But I don't have to worry about reaching that breakpoint, so much haste on my gear already.
As far as the rotation and opener go, check out kuni's frost guide for that.