hello
i also would go for physical RDM (read best practice sql from vmware though) and i would go for vDS if your license allows it ofcourse.
but i would recommend using 2 single port x520 card. this way you can have failure on one card.
you are going to use the full 10GB only for storage?
you can use de 10GB card for everything i think. split up the bandwith. 1GB management network, 1GB vmotion, 1GB fault tolerance, etc, and example 4 GB iSCSI. i dont think you need 2 switches then if you connect both 10 GB to the switch and vlan everything.