Hi! The first thing is, he will be very scared in a new place. He may be puffed up because he is scared, nervous, or not feeling well. A wellness check is always good with a new bird. Offer him his regular diet,,you can always transition later. Cockatiels will drink water when thirsty, I noticed my own don't drink that much either, in my opinion, but they are ok. Try to cover the top and two sides of his cage so he feels a little safe. Talk softly to him, don't force yourself on him right now, he will need time and patience to adjust to his new home. Put a night light in his room so it's not completely dark , move slowly and quietly around him, don't stare at him..as far as he's concerned, your a threat right now and want to eat him. Time, patience honey, we are here..and congratulations on your new baby!