First, your painting and converting are very nice. I especially like the ammo packs on the Tactical Marine's shoulder pad. Neat idea.
Your list looks very fun, and even competitive, but I noticed one illegality: Attack Bike Squadrons must have a minimum of two Attack Bikes unless you're playing BA or DA. It appears that you are playing Ultramarines, however, so you'll need to adjust something there.
Post some Battle Reports in the appropriate forum for us to read and post more of these pictures in the Painting forum.
NewHeretic