Cute little cham you have there. Chameleons are awesome pets, but they're very different from other pets, and even other reptiles.
You came to the right place though - this site is filled with many friendly and helpful people.
I would very strongly suggest a few things. Your cham needs a series of horizontal branches to climb on - especially one that allows him to bask, located about 1 foot away from his basking light. The more foliage the better. You might not always be able to find him in there, but it will help him feel much more comfortable. And like the previous posters have mentioned, you'll need a UVB light - go for the the linear tube version opposed to the compact bulbs, they're safer, better, and light the cage better.
Live plants are also a great addition, as long as they are non toxic for your cham. Pothos are very popular amongst keepers and are extremely easy to care for.
A baby cham, like yours appears to be, will need to be fed much more than 2-3 crickets a day. Since he is doing so much growing, you should feed him as many crickets as he's willing to eat (Probably around 10 - 15 small crickets daily). Make sure though that the crickets are no wider than the width of your chameleons mouth, so he doesn't accidentally choke. Insects will need to be dusted with Calcium (without d3 or anything else) every day, and twice a month you'll need to dust them with Multivitamin and Calcium with D3 in it.
For handling, you'll need to be patient, otherwise you'll stress your little guy out. I waited until Mr.Pink was comfortable around us at feeding time (didn't "run" away from us) until we tried taking him out. We only take him out for short periods of time, unless it's to go outside for some real sunlight in the summer.
Unfortunately, chameleons do not change colour on a whim. They will get all puffed up and change to a stress pattern if you spook him. As beautiful as that can be - you don't want to cause stress in chameleons. Ultimately it could kill them, but not before causing a slew of other health problems. The dark dull patterns you're probably seeing are an indication that he is cold and wants to bask. (If you give him a basking branch he will go to a nice green colour when he's warm enough) Darker colours absorb more heat than brighter ones, so that's why they do that.