1) Only three bosses can block: Barbon, Zamza and Shiva. Shiva always blocks with no damage, so he is no target. The other two block sometimes with no damage, and sometimes with damage but no stun (this is the version we're after). It works best on Zamza, where you indeed can chop off one lifebar or more in one move. Barbon usually blocks with decreased damage and falls after a while (I haven't quite worked it out yet).
Both ninjas and kickboxers can block, but they take no damage.
2) The hook gives three hits if you're at point blank, face to face with your target. It only gives four hits if you're actually inside the enemy (after a jump + attack down usually).
This is all in my faq by the way. It's almost mandatory if you're making a run.
http://www.gamefaqs.com/console/genesis/game/6774.html
Now, which is faster, Axel or Max? I really don't know. Max is stronger but worse against many enemies at a time. Although I love to play him, I usually go with Axel if I'm to get trough Mania alone. But when I play mania, I play safe rather than fast, so who knows? Maybe even Skate or Blaze could be faster. My bet is to go with both Axel and Max though :)