In general, afaik, team strategies are not really developed in depth. This is simply because actually governing the robots is exponentially harder than anything else, and a robot that does not know where it is on the field, where the ball is or is unable to move is also useless - no matter what advanced tactic you decide to deploy. And these are REALLY hard problems!

Other problems are: understand which side of the field is actually yours (it's not uncommon to do autogoals, since the field is visually symmetrical), how to understand where you are after a referee repositions you, how to distinguish friendly robots from adversaries, not fall down every five seconds.

And still the game is driven by simple hardware physics: the robots engines tend to overheat very often, which basically results in the robots "melting" on themselves since they can't support their weight for very long. And there how much money a team has to spend comes into play heavily..

So to get back at your questions, not much. In general if you can shoot in the general direction of the enemy's goal more often than your adversaries, you will probably win =)

Not much; a couple of cameras (which are not in the eyes), a motion sensor, microphone/receiver for audio and a couple of bump sensors.

Aldebaran (the company that makes them) provides the robot with a default OS. The main problem is that it's not really efficient nor stable, so in general teams have to reimplement nearly everything. But to play around with it it's probably decently accessible - as long as you don't do anything really innovative. Aldebaran's website gives more info about it.