Chicks should be started at about 90-95 degrees for the first week of life, then reduce by 5 degrees every week until you reach about 70 degrees. If the temp is correct, the chicks will be evenly distributed under the light, and they will be wandering around and peeping in a happy way. If they are huddled in a pile under the light peeping madly, they are too cold. If they are laying in the corners, they are most likely too hot.
Feed and water should be available at all times.
Your last question is a tough one - hens certainly make their nests out of all sorts of natural items, including leaves and pine needles. When my hen raised her batch her nest was a mixture of all sorts of things. However, when I am raising the babies myself, I think the cleaner things are the better. I would use wood shavings.
Have fun! I love Australorps!