Thanks for the additional information. it is helpful.
Dogs are very opportunistic to say the least. Since there was a puppy there before you moved in, his initial fear may be from moving into a place where there was already the scent of another dog. That would make your new home the territory of another dog which may have made him a bit fearful.
When he went and hid due to it being a new place and the odor of another dog (which you likely would never notice), you comforted him and showed him attention and maybe even rewarded him with tasty treats while trying to lure him out. He learned quickly that when he hid in the other room, you showed him attention. They learn real quick how to manipulate their owners.
When you stopped trying to coax him out, he started barking and you responded by coming to him, so then he learned that barking worked. Now I don't know your current housing situation, but assume you have neighbors that will be disturbed if you let him bark. However, if you keep going to him, he will continue to bark. So we need to approach this a little differently.
First give the whole place a good cleaning especially wall corners and go up the wall a little when cleaning. Clean with an enzymatic cleanser. You can get a special light which will show up old urine stains on the floors and walls. Make sure those areas are thoroughly cleaned until their is no lef over odor. As I mentioned most cleaners fool our noses but not a dogs. Only enzymatic cleaners break down the protein and totally remove the odor. With the odor gone, he may no longer be worried about other dogs.
The second thing I would do is install some children gates to block off the bedroom and bathroom so he is unable to even go into those rooms until you want him in there. If he doesn't voluntarily come out in the morning for a morning walk, then don't allow him in at night either until you get the behavior under control.
When he grabs the leash, don't move at all. One way of stopping him even from grabbing the leash is to start out your walk with tasty hot dog slivers in your hand and feed him one before you start moving at all and let him know you have it. You can drop one every once in a while as you are moving forward initially. If he wants to grab it quickly he can not have anything in his mouth. That doesn't seem to be as much of a problem as his hiding and barking is.
It is going to take him some time to adjust to his new surroundings, but if he is in the main living areas where you are, he is more likely to get used to your new place faster. So I would get the light from your hardware store that shows old urine stains and do some cleaning and either install child gates or otherwise block off those rooms.
Doing some obedience work with him might help as well. I don't know if he has had any before so the following site mibht be helpful in teaching owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
You admit that he is a bit spoiled so training will help him respond better to your commands.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.