Me and another player recently joined the ladder. Our first game against another team with a rating of 0, which we won. This one and first game gave us a rating of 1600+ and the other team got a rating of 1500+, much higher then many other teams. How did this happen?

I believe that the ladder makes an assumption of a certain baseline rating, absent any completed games. From looking at your situation, the baseline appears to be a little below 1600. So your team goes up a bit above that baseline, and their team goes down to below the baseline.

This will be rectified whenever you or the other team finish a second game and you have another rating to be based off of. This rating is basically a placeholder, and until you finish enough games to get a rank, there's no bragging rights or anything else to come from it.