Yes.. 200 max on each leg.
No. Breakers can total far more than the mains. The mains are protected by their own breaker. It is assumed that you will never draw the maximum current on every breaker simultaneously. If you did, the main breaker on a mains panel, or the feeder circuit breaker on a main lug panel would trip.
Always remember, breakers are not there to protect the devices. Breakers are only meant to protect the wires.
Hope that helps,