As a general rule, one chook = one egg a day. May drop off as they age/if they are unwell.
We had Sussex chooks - white with black accents
in Central QLD, so very hot and humid. As long as they have lots of water and some dirt to scruffle into, they'll be happy. (Also just got generic laying pullets when we couldn't source sussex - either red or black).
One thing we used to do on really hot days was add a bit of treacle/golden syrup to their water. it helped perk them up (like gatorade for us).
ETA: get them as chicks if you want to make sure they are tame, but they are more hard work. get point of lay pullets if you want eggs ASAP (also you're guaranteed you won't get a sneaky rooster - we had a few surprises when getting chicks
Edited by asdf89, 19 December 2012 - 10:30 AM.