The CB payments would be the child benefit payments alright, 160 per child, thus 320 as you have 2 children. I am assuming the quarterly payment is the early childcare supplement, I am not sure of the exact amount that is given for this, but it sounds about right as you have 2 children (I think it's in the region of 1100 or a little more per child per year, so the 550 quarterly sounds right).
The child benefit will continue until your child leaves fulltime education (normally at 18, but you can get it extended if your children go onto fulltime college/uni until the age of 21) and the early childcare supplement will continue until they hit the age of 6.