1.Misting should be done once every night unless it gets too dry. You want the substrate to dry out a little the next day or it will grow mold. I mist every night, spray all the sides and the fake plants, I dont use water bowls so I spray them down really well so they have enough to drink.
2. That is normal, the top layer will dry out before the bottom layer. That is exactly how it should look the next day after misting that night

3. Paper clips should be ok if there are not any sharp ends sticking out that the geckos can scratch themself on.
4. The temps sound ok. As long as it doesnt get above 85 for a long time.
5. You can test out the amount of cgd you use. Try a bottle cap and if it's gone then the next feeding add more until you have a little left the next day. You can also keep it in for a few days until it starts molding.
If it's a baby then it will eat very little but adults can be pigs when they are use to eating it.