Oil prices were 50% cheaper not too long ago, and the food wasn't significantly cheaper, so I can't see how more expensive oil will make the food prices "skyrocket".
Yes, and in a prisoners' dilemma with thousands of players, someone is surely going to defect and sell their stuff cheaper to undercut the competition. I don't think I've ever heard about large scale collusion to fix prices in food industry, and I won't hold my breath for it this time.
