Well since you only got him two days ago, I am not surprised he is kind of quiet and such. Being in a shelter and then transitioning to a new home is very hard on a dog. Give him some time and he will blossom. But we're talking months here, not days. He should open up a little more every day.
I can at least tell you that's how it has worked with my dog. He was very quiet and withdrawn when I first had him. He didn't bark much, wasn't very interested in food. He liked his toys, but was very possessive over them. He hid under the bed a lot. 6 months later he scarfs dinner down, barks when someone comes to the door and LOVES to play. He still has some issues from the shelter/being a stray. Like he is not very well socialized around other dogs. But he's really blossomed and grown in confidence since I first got him.
Other than the crate, I would recommend you enroll your new pup in obedience classes and start practicing NILIF (read the sticky at the top of the training forum). These will increase the bond between you and your dog and help him with his confidence as he realizes his place in your household. Bear in mind too that training, especially housetraining, is not an overnight kind of transformation. It takes time and patience.
Good luck and don't forget to post lots of pictures!
My baby came from a shelter 3 weeks ago, and his personality has really changed since then. He is more outgoing than the first few days. If your boy was neutered before coming home, he could stilll be groggy/ in pain from the surgery.
