Gecko's shouldn't really have light at all, unless it's for supplemental heat. What bulbs are you using? Try not to leave food in overnight next time. Crickets get hungry as well, and can start picking at your gecko. Great to hear that he ate the gecko though! :) Not sure if you would want to...
That's unhealthy poop, but leave it alone. They're not supposed to come out their hides for no reason. You can get a plastic syringe and feed him through that, and have him lick. Never force anything into their mouths.
I'd just spend some money and get a real hide. The entrance hole is way too big, he won't feel safe in there. They should be able to hide and have you not see them. I wouldn't mist too often. The mixture you're spraying might not help, the calcium is useless in the water if it's not going into...
Don't handle him at all, this will stress him out even more. They should only be handled if they're comfortable with you. Take another picture of your new setup, and is the right side the hot side? If so, the hide without the coco fiber should go there.
Don't use see through hides, they won't feel secure. There's no need to put all the extra decorations. Keep it simple until he can start eating. Use forceps to feed and don't leave anything in if he doesnt eat it. Try feeding him mealworms, he doesnt need to hunt for those.
We're talking about leopard geckos, right?
Take a picture of the tank, and a picture of him if possible. Don't force feed, it will only stress him out more, making him not want to eat.
Welcome to the forum, have you ever looked into crested or leopard geckos? They're the most common geckos. There are also lots of arboreal gecko species similar to the ones in Hawaii if those are the ones you're interested in.
Sorry for your loss, and Jorge, make sure to get repashy calcium plus, it will save you money as it's vitamin and calcium, and it can be used in every feeding.