A model with 10 wounds would be counted in the 2,3,4,5,8 and 10 category.A model with only 2 wounds would only be counted in the 2 wounds category.
So chaos warrior with sword and shield would be counted once in the 'models with a wound value equal to or greater than 2' and would add 1 to the army score.
A khorne lord on juggernaut would be counted in the 'models with a wound value equal to or greater than 2,3,4,5,8' adding 5 to the army score.He would also count once in the rend -1 and damge 2/d3 categories meaning in total he would add 7 points to your army score.