I honestly don't know what they weigh right now but there is a definate heft to them when you pick them up, they weigh alot more than they look like they do. Very solid.
I scrub my 5 gallon waterer out with 50/50 bleach and water once a week, as well as my feeders. Then I spot clean my brooder house at least 3 times a day to prevent any packing down of feces, and stirring the shavings. I check and re-check waterer and both feeders to make sure they get as much food as they want in those 12 hours. I also spend time with them, just watching over them, looking for injuries, illness, making sure the flock is in good working order. I pay close attention to temp fluctuations and keep any stressors away from them. Only my oldest son who can be quiet and responsible is allowed near my meatbirds. I hardly let me husband near them. No dogs, cats or anything else. I try to keep them nice and calm.
I feel these things are a NO BRAINER but alot of people just want to toss them grain and water and wait for a perfect meat bird. There is more to it than that.
I also just treat them nicely. Like or better than I treat my layer flock. I bring them treats, bugs, worms, some scraps. I toss scratch in the shavings and they do scratch around for it. If I were raising them in the heat of summer I would make sure there were vitamins and electrolites in their water at all times since hefting their weight around in the heat is taxing.