Heyyou,
Plastic gear boxes do not need any break-in. The motor should be run-in though. You will need to dosmount the motor and run it at med speed for at least 1/2 hour in both directions. You can use your batteries for power or do like I did and use an HO train transformer. For metal, you can go to the FAQ and find your answers there. Should be able to get answers on battling as well.

Jim