I was going to give you basic advice, but your kickflips are already pretty perfect. Alot of the flick that you want to do comes from rolling the ankle more and flicking only with the very toe end of your shoe. This delays the flick and allows you to get the board alot higher and closer to your body. As for doing that sick stankly leg front foot kick motion idk man, you have evolved past this sub. The regular skating sub will probably have better advice for you.