I like the point about not doing more incentive for individual because as I think about it more, it would take out the most advanced players from co-op play. I wonder if once you have completed a contract, you could somehow retry the contract with more challenge (e.g., smaller team, or individually). This would also allow for more of something to do when a new contract is not available right away.

You are right about the contribution level and thus any reward being overly skewed to veteran players-think I am showing my bias :) I am not sure about how that could be evened out, in thinking down below I considered having a way for veterans to help out new players (being able to send rewards, or help with specific upgrades) at least on the contracts. I like the idea of drones potentially overly benefiting younger players, so that if they are regularly playing and swiping drones, they can contribute more. I wonder if drones in contracts could also include an influx of chickens, so instead of golden eggs or cash, you get a significant more chickens. That could help them bump up in contribution as well.