AR7 is a good shout, they're more than just a park ski. Similar ski could be the Nordica OMW, or the El Reys (step up from the AR7s). The Infamous would be a good start out freestyle ski, alternatives could be the K2 press, Line Afterbang and a few others.
It depends what you want to do. If you're going to spend all your time in the park then a pair of symmetrical twins (same tip and tail width) would be great. If you spent more time outside of the park (which it sounds like you do at the moment) then a pair of non-symmetrical twins would possibly be a bit better. If you get non-symmetrical twin tips, then I'd probably suggest you get them mounted either at the factory recommended setting, or maybe just 1 or 2cm forward.
It really depends you want. I like to do a few laps of the park, then hit groomers hard, and I own a pair of Atomic Punx - which are designed more for the park than the whole mountain - but I don't have any problems with them. Realistically you'll want a softer ski for your first park ski, as they're a little more forgiving when you mess up, and you'll find it easier to learn to butter, spin, etc. Chances are you'll trash your first pair pretty quick, so it could be worth looking at some of the offers on last years models, unless you really want this years graphic or something like that.
Hope that's helpful?