1: It'll probably be like $70 or something for the bundle.
2: If it's your first time playing, it'll do you just fine. They are a lot better than what they used to be years ago. When you start playing on the expert level, you'll probably want to invest in a Red Octane Ignition Pad(around $70 now a days)
3: I prefer playing alone at the arcades, so yes.
Also, #1 rule when starting DDR. DON'T STAND IN THE MIDDLE THE WHOLE TIME. Or when you step on a panel, don't always go back to the middle. The majority of people that play for the first time do this(I did), and while it's ok for beginner songs, it won't help you out once you start playing a little bit more difficult songs. So basically just keep your movements flowing. It'll also save you energy so you're not moving twice as much by going back to the center of the mat after every step.
In other words, don't do this(watch the guy on the right):
Do this: http://youtube.com/watch?v=_vrXSneQBcY
Konami probably won't have wireless pads, but I'm sure some 3rd party will have them eventually.