When you are getting ready to publish it you can change the option to make it copyable or not.
Because you can make your own levels
you cant but you can post stuff in levels to make it go to the public
no just beat the gardens
In one of "The Canyons" levels In littlebigplanet 1
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.
Theres many online levels, so search,How to Make Pokemon Costumes and there should be a few how to levels :)
On DLC's
there a total of 25 story levels
Just make loads of levels and join them up to form a world
no you need to purchase the new game
From the African levels
there is no official Mario costume, but check some online levels, I bet you can make one there.