I also have 2007 F350 dually, but mine is cab and chassis, so might have beefed up brakes. I know my suspension is much stronger than standard dually.
I still have the front pads that come with the truck 3 years ago and don't like the brake dust, so already bought semi-metallic by Bendix and trying to find time to change them. :W
For cars I was able to buy Akebono pads, that make no dust and seem to last forever (I measure the pads after 60k miles to have about 25% wear) but don't think you can buy Akebono for F350.
My front pads are over 6" long, so you can compare to yours.
2007 did not come with exhaust brake, but tow mode will downshift for braking.