People post pictures of necropsies they perform on their dead birds. I'm not an expert on chickens, but maybe a picture would help someone else if you notice anything strange. Especially if there was an attack. I would not worry about posting a picture of a dead bird. At worst, you could always...
I am old school, and perhaps sometimes overly concerned, but my rule of thumb is to never let my animals run out of water. Considering your heat, and the fact that they are drinking their water dry, I would certainly consider other options for water.
It's great that you change their water twice...
Do you keep water in the coop? I have both feed and water in my coop just in case something comes up and I have to leave my girls locked up in the coop for a day, or two. Considering you mentioned that it has been hot where you live, and that the cockerels were found under the nest boxes in the...