I think the solution is to get the idea guy down in the details of each idea. Bring him along for the ride and let him come up with lots of micro-ideas. It can be very useful to have two people thinking about the minute details, especially if they balance each other. Involve him in the thousand tiny decisions you have to make while implementing an idea.

Get him to stop looking at competitors. It's nerve wracking, demoralizing, and distracting. You guys probably have more than enough ideas by now, if you'd just focus on the most promising ones your competitors might start looking at you.