Hello there ,
Im fairly new to owning my eclectus Jack, actually a first timer to owning any bird, well had a budgie when I was a teen. Jack was 14 weeks old when I got him, that was about Sept, so he would be roughly 6 months old or so.
I remember when I first got him, I was nervous as hell, as I never had a parrot in my life. You have sparked some early memories of my jack , what I see in your posting.
When I got him home, I took a couple of photos of him sitting on his new playgym, I think I posted these pics and also sitting on my daughters arm, this was his first few hours with us. My profile pic was taken just hours after we got him home, I couldnt wait to take piccys of him. He seemed quite happy to sit and not really go any place, Im guessing , checking everything out, new place , new faces. Jack really didnt eat much either, was terrified that I had made a mistake in getting him and would I be able to handle or look after him. I gave him grapes , which he seemed to take too quite a bit, loved them. he wasnt interested in toys either. So I thought I had a bird quite different from all the things I had read.
You have only had him 3 days , I really wouldnt panic too much. It does take a while before they start to become comfy in their new home. Talk to him often, offer grapes and see if he does take this , unsure if you have done grapes ?
My Jack loves to eat lots of things now and grapes it seems has gone down his list a bit. Jack loves snow peas, snowpeas sprouts, mini cucumbers, corn, celery, apple & bean sprouts ( I took new pics which I posted, he got caught eating in my fruit bowl ). He will eventually come round, he needs to feel secure in his new environment and one of the things you asked , Most definitely he would be missing the person who raised him or where you got him from. It can take a while for him to start to come round. But when he does, you will enjoy every second of him.
I would have your parrot out to get used to things, but that is really your choice, but I think keeping him in his cage in his new surroundings wont let him get used to anything, but if he chooses to stay in his cage, dont take him out.. But Im only new at this , I think just a little time he needs to get used to his new home and owners. Keep talking to him.