Re: 3 day pass -- it's covered as the above have well described.

As for countdown -- Times Square may be lively, but you do need to get there a bit early. Trying to get there 11:45pm might land you very far from where the actual countdown is. It'll still be very crowded and lively (actually, a lot of the places are). It's just that you might not see the main area.

Or you can go to Lan Kwai Fong, which will have strict crowd control measures too. Basically though most popular places will be extremely crowded.