RE: breaking-in
An engine should NEVER be run without a load on the engine. For car engines, this means the engine should never be run at wide open throttle (WOT) when it is lifted off of the ground. You can overspeed the engine doing this and cause serious engine damage.
However, I don't believe in idling an engine to break it in which is common in the car community. Here is what I do which is completely different then what many car manufacturers state. I believe that they are wrong and I have never ruined an engine from breaking it in this way.
Start engine,
Tune engine so the engine is running just past the 4-2 stroke point at wide open throttle (with it running on a smooth surface such as asphalt or concrete). The engine will be hot enough not to damage it from 4 stroking but rich enough to keep it from overheating. It will not however be very fast or perform like it should-thats ok, its not broken in.
Find a nice parking lot and drive it for a couple of tanks where you go to WOT and the let it coast at a high idle and repeat. With each tank increase the amount of time at WOT and decrease the coasting/cooldown time. With each tank, you may want to slightly lean mixture until you can maintain a temp that doesn't exceed 250 deg F when run at WOT for extended periods.
You'll have more fun with your new car and breakin instead of sitting there watching a car idle and waste gas. One word of caution, KEEP an eye out on the temps and make sure it doesn't overheat-exceed 250 deg F.