Gorgeous horse. Mine has a lot of white too. Rubbing alcohol and Quic Silver are my best friends for keeping him clean.
In your jumping picture, you are WAY ahead of him. Shorten your stirrups a hole or so, and put your weight in your heels. On the approach, stay in something of a three-point or so, and WAIT for him to jump, don't try to jump for him. He should be carrying you. By staying slightly back in a three point, but still out of the saddle, you shouldn't have a problem getting off his back over the jump, but it will help you to keep from getting ahead of him and anticipating his jump. The shorter stirrup and putting weight into your heels will give you a more secure leg and will help you better balance yourself so you don't have to reach and lean on his neck quite so much.