Chick starter should be fed for the first 6 weeks. Clean the litter as often as needed. Wet floors make for a cold and damp house, which leads to all sorts of problems. When my chickens were 10 weeks old I moved them into a large walk in chicken pen. One end of the cage was tarped to protect from the weather.
Tree branches make good roosts and can be changed easily as they get soiled.
In the evening close up the cage to protect them. Keeping chickens is a great experience and I would recommend it to everyone. It is fun to watch them rooting in the yard for bugs. Another bonus is that chickens greatly reduces the amount of bugs in your flower beds and garden. My son loves the weather stuff and I love the garden stuff - lol.