first of all: congratulations
Your excitement is evident from your words and the complete absence of any punctuation, commas or real sentence structure lol.
If it's an outdoor/daylight affair, either camera should be fine as there will be lots of light. Of course, the lens plays an important part too - but the 7D may well be better at tracking and maintaining focus, perhaps.
While I don't dabble much in sports-photography, a fast shutter-speed is a must for capturing the action. What I've noticed in many professional soccer-photo series, have a few real close-up of a player or two engaged in a shot, heading the ball or simply running into each other. Keeping an eye out for when the ball is about to come down among several players, is where the really exciting shots emerge.
Personally, I find wider-angle soccer shots a little drab - you can't really grab much of what's going on and it doesn't really say tell much of a story. When soccer-shots really pop, is when you see the very intent faces, twisted in some extreme grimace of exertion and intent.
Also, try and be conscious of changing levels so they aren't all at eye-height. Creates some variation. And make sure you throw in some that have a shallow DOF...creates some "intimacy" and "presence".
Good luck with your assignment/job and please, if you can, share some of them here with us! Looking forward to seeing what you get