Frozen fruits (not the packaged "cups" with 30g added sugar) are great if for some STRANGE REASON your birds don't like watermelon slices from the fridge. Maybe they just got tired of me giving it to them after the first week of watermelon.
We tried a ryobi mister/fan, but they didn't seem to care and the battery would run out long before the day was over and the fan wasn't very powerful even if you got extra batteries. Probably don't need a tornado fan, but it sure does feel good. Just remember it's a solid 10 degrees cooler in full shade than in full sun, so 90F will feel like 80F and won't be so bad. We also have chicken cameras so we can check on them anytime and go out and tend to them every day.
Definitely watch out if anyones going broody and staying in the coop or even possibly eatting eggs. Even if the coop has windows, I sure wouldn't want to be sitting in there all day.
Sometimes their combs might fall over, but this can be a way for the hen to stay cool rather than being in distress. Look out for the wide wings and panting.
If your bird is struggling, rapid temperature changes can actually make them sicker and inhibit the immune system. I actually found out from a Kentucky derby horse trainer that horses get so sick they die when their barns have a/c. I personally wouldn't dump a chick in an ice bath, but some people do in an emergency. Some people even advice not putting a bunch of ice in the water for the same reason. I'm not sure about hosing them down because their feathers are water-resistant. The best thing you can do is to not get chickens that will struggle in your climate (hot or cold), and then work on the coop placement/accessories.