50mm are always great in my opinion. I had a lot of fun with mine back in the day.
I was more familiar with Nikon but the 7d should be more than capable of taking great video if stabilized.
http://www.speedhunters.com/2014/02/...ear-some-idea/
Here's a speedhunters article of some gear.
They have a good handful of articles on automotive photography.
Not by any means saying speedhunters is a go to for photography knowledge but they do have quite a bit of experience to share.