1) Toss up. Blow is pretty useful for stunning pesky monsters, while Hurricane Sword is okay for mobbing.
EDIT: Personally, I'd go with Blow, since it's an essential 1-point-wonder for PvP, too.
2) Rage Explosion makes all of your physical hits critical. Elemental hits such as Whirling Sword are not affected.
3) Most people leave kicking at 1, some people max it. Having it at 2 might not hurt you *too* much, but if you plan out a build and end up needing 1 point from somewhere, reset it or restart x-x.