Hi AnnaAugusta,
I'm new here too.
I have to say that your story sounds like a classic gifted child story to me! I have heard that story many times. The descriptions you are giving of his behaviour is also classic bored/unchallenged behaviour.
I'm not from the US so I dn't really know all the acronyms. Is the MAP a normed/standardised test? If so, that would tell you a lot about his levels capared to other children.
I think what you do next depends on what is best for your son, and that will depend on individual cercumstances. But the first thing I would do is what your already doing - find out what you can about giftedness. There are people here who have been researching this a lot longer than I have but a couple of things that really hit home for me were the simple lists (for example this one:
http://giftedkids.about.com/od/gifted101/a/giftedtraits.htm ) I can see your post ticking a lot of those boxes, can't you?
And yes, I can tell you getting in trouble can be a lot less painful than doing work that is too easy - at least it's more interesting!