Make your motorcycle base, delete the area where you want wheels, put a thin layer behind the area the wheels should be, glue those on then add rubber wheels put motor bolts add a rocket if you want, add a area where you can grab, put a grab switch on it, attach it on to the motor bolts then you can color it with your choice of stickers.
You cannot.
use an emitter
you cant
With a scoreboard
Make a good level
Make a really good level
Make a good level
Because you can make your own levels
Use options to make it a favorite
Yes, the motorcycle is not street legal and they did not make many
You just go to create mode and make anything
Hard question, but in my opinion, yes. In ModnationRacers you can make better mods and tracks + it's easier to make karts. But in LittleBigPlanet, you can create whole levels instead of tracks.