Never tried em, always just stuck to regular deads. Was wondering about form on this one; do you touch the 'bar' at the bottom? Im thinking the bar should not go passed your knees.
height is dependent on what your options are. ideally, it should be center of your kneecap. my rack doesn't allow that so mine is done from the top of knee. if you have to bend your legs because it's so low, that kinda defeats the purpose of the movement, might as well pull from the floor. JMO.
yeah you touch the bar at the bottom.. you can reset your grip or you can touch and go. (mostly a large clang and go if you go heavy )
most set it either mid knee cap or 1" below, helps the lockout portion of the deadlift. and definately reset each rep, if you bounce the weight it's going to be a lot easier. pull from the floor one week then rack pulls the next week. rotate each week