This is my first first iPad and I was under the impression I'd be able to stream content (video and music most specifically) from iTunes yet I can't figure out how. Any help?
While sound/video is playing, double-press the home button and swipe right on the bar at the bottom (to get to the stuff to the left). If your iPad can see your atv2 on your network, an airplay button (a small rectangle with a triangle) will be between the forward button and the volume slider. Touch the AirPlay button to choose the output source.
You can. That is called Home sharing. Make sure you are signed in in the sys pref page. Then open the video app, and you should see shared libraries in there.