The equipment you chose is what I got for my starter kit for weddings a year ago. If you want some quick wireless capabilities, buy a yongnou transceiver. It's like $40 and works up to shutter speed 1/200 just fine.
You don't need a diffuser. Bounce off ceilings / walls / t shirts. Even if you're outside, covering the flash up with a piece of paper (to diffuse) or bouncing off a chair / person / paper w/ cardboard backing is superior to 95% of diffusers.
You'll really love your 5d Ii. It's a superb camera.
Good luck! Post pics

You'll see how hard weddings are and earn a new respect for em. Don't forget that the most important things in a wedding include ALL wedding rituals. You miss the first kiss, you auto-fail.