Aww, what a cutie! I know, I love watching mine hunt for crickets, so awesome!!

The main way you can tell that they're eating the CGD is by checking for poop, otherwise it's always a guessing game since they eat so little. Sometimes I can tell when I see little splashes and "footprints" on the paper towel leading away from the little dish. I used to worry too, but believe me, unless they're full from crickets, they'll eat it.

As far as portioning the crickets, I guess you could always try doing it beforehand, i.e. emptying them into separate containers, but I'm sure that would get to be a real hassle. Or ask them for separate bags at the store haha I only have one crestie at the moment, but I know it is hard to get the exact amount of crickets in there that you want. Just a hit and miss kind of thing I suppose. Some of the more professional crestie keepers might have better tips

Also, I mist twice a day, but as long as everything has a chance to dry out before you mist again, I'd say three times is fine.