Setup is standard powerlifting setup, how much you arch is up to you of course.
Grip width is whatever feels best.
You can "pull the bar apart", especially useful when using a wider grip, but you have to see if that bothers your elbows or not.
SWRGB does little for the lateral head imo, but really helps make the arm have more sweep from the side, and make the long head look thicker... It sort of hits things on the inside though, i.e. medial and long head, far more than the outside.
Pin CG is more lateral head esp. if you flare and some medial, and that's about it for me. If you're already doing pullover+extensions, then this complements them well because they hit the long head alright...