$1200 right now. Which is right there with a new Quark carbon. It looks like based on some reviews I've seen, it limits your cornering by maybe 1 or 2 degree. I'm not sure how significant that is, not having raced in a while. They look pretty beefy so I think they could take a few pedal strikes (and I think the battery would hit first, which is probably a good thing). DCRainmaker has 175mm cranks, and got 31* with the Powertap pedals and 33* with regular Look Keo pedals, in an informal test using a phone level app taped to the bike.
You have to use both pedals I think. You certainly have to use the left one, because the left one is the master and the right is the slave.
You also can't do one leg drills with only your right leg and still get power readings (not sure this is a real issue, but I guess it could be). They will probably fix that relatively soon, they're aware of it and have submitted a report apparently.