Actually if you read George Morris (or any of the other big time hunter seat equitation coaches) he says you do turn your toes out with English riding. Very slight, about 10 degrees, with more weight on the inside of your foot (so your foot flexes out). You have the most effective use of your leg and most secure foundation this way.
Western? Uhh...
As far as stirrups go, you should use them, but be ok without them. I imagine your leg will be stiff if you're making an effort to be light in the stirrups... ?