There seem to be two aspects to the "dodge". One is actually dodging a direct attack. Hanzo stands there and if the attack misses, it says "dodge". I believe that is what the stats refers to, the chance for the attack to miss. But Ezio also adds a whole lot of movement (what you see on the screen) where he is not attackable. This would fit our definition of "dodge" but might not be stat related, but rather character ability to avoid the attack whereby the dodge stat would come into play.
That's actually wrong. When ezio is using all of his skills he is invulnerable for some reason so nothing can hit him, or do damage, he'll you can't even try to cast or attack him. It's pretty dumb since you can't even cast a heal. So he is avoiding any hits or missiles flying towards him if he casts an ability before they hit going invulnerable however it is not technically a dodge by the way it's defined in the game.
You are right about the first statement. The dodue rating on a hero is the natural chance to dodge an attack and some heroes have more dodge then ezio. However ezio has a skill that guarantees he dodges an attack every 11 or 12 seconds regardless of what his dodge rating is.
Conclusion there is regular dodge and skills that guarantee dodge every so often or some other circumstances. Ezio has both and on top of that all his skills make him invulnerable which is why he is broken as fuck. He can literally be invulnerable for 30 or more seconds sometimes while still doing full damage himself.