I'm in the Northeast so my input may be of limited use to you. I can't say what variety it is but I can say (assuming the red on the leaves is not a seasonal color change) its not a Silver maple, Sugar maple or a Norwegian maple.
I have never heard of pruning a maple. In my experience they tend to reach both high and wide. I also usually only see a few branches on young seedlings like yours has. So I wouldn't be worried about the lanky-ness. I would however be a bit concerned about the state of the taproot. Since maples are known to be so large you certainly want it to have a very strong root system, and the transplanting likely disturbed that. If you really want a maple I would suggest picking up the "helicopters" from your neighbors yard, sprouting them, and then planting directly where you want it.
Best of luck getting an ID!