Impossible Warrior challenge

[laffwis]

hi everybody,
after finishing mage on impossible, i decided to try it with a warrior, giving me a bigger challenge.

could anyone of you tell me which traits (attack, defense, rage, intelligence, mana) should be given the most priority?

and from what level on should i start chosing leadership when i level up?

and which units would you suggest for the start?

thanks in advance