Unless you know how much you'd get for selling it, get some good quality sleeves for the deck, and use it. It is a really good card, and is beneficial in many decks.
I'd most likely sell it. They're really useless in ones, though if I had 4 I guess I'd just use it for some weird deck or collectible set (which I'd probably end up selling =/).
Depends. If I sell it, I want decent money so I can buy an MT box and get another. I would try to get more and play them but one isn't great. They're nice and shiny though. $.$