ok for the 450 out , you need to land on the rail whit your shoulders facing down the rail. braking your upper body form your lower body. has your are coming to the end of the rail , you can bring the toes of your front foot up , giving you some grip and some thing to push off helping you for the spin out .keep your back hand near your back hip , giving you a bigger spin for the spin out a solid pop will help you a lot for this too . once your off the rail , its basicly like a 360 , look over your shoulder and spot the landing .
helps?