1) for D20 modern, I've taken combat martial arts, which makes it so that unarmed damage can be either lethal or non-lethal. I have also taken brawl which makes you do 1d6+str unarmed damage and improved brawl which gives you 1d8+str unarmed damage.
Since I have combat martial arts, I get to make an unarmed attack for 1d8+str and do lethal damage, right?
2) in d20 modern, if you multiclass (i'm a level 4 strong hero / level 4 tough hero), can you still gain a class in either level when you level up but they have to be within one level like normal D&D?
3) If i were to take the knockout punch feat which makes your first attack against a flat footed opponent automatically crit, it says right in the description that it does nonlethal damage. would it still do nonlethal damage even if i have combat martial arts?