All chams grow at different rates, it's possible he could be anywhere from 3-4 months old depending on how that cham personally grows. For a young cham you should be feeding anywhere between 15-20 crickets that are about 3 weeks old depending on its size. The rule of thumb is nothing bigger then the width in between yours chams eyes. For treats you can use meal worms but not many as they're pretty much junk food. Once your chams older then you can introduce other feeders as well. If you find roaches small enough and silk worms, you can feed those as well. As an adult you can feed every other day.
Don't forgot you'll have to have a dusting schedule as well.
You should still have a dripper, just because you don't see your cham drink from the dripper doesn't mean he isn't. Of course, mist 3-4 times a day to keep up humidity and have real plants as veileds do enjoy some veggies.
Let us know if you've any other questions!