Please don't accept this behavior as par for the course of owning a Cockatoo. We have a 30 year old U2, and two small children. Chipper isn't fond of them or my husband. He is NOT allowed on the floor. When he is on his playstand, he gets treats, toys, praise, attention. If he ventures to the floor, I do not talk to him, act stone cold, and ask him to step up. Then he goes back to the playstand. This is called station training and it is Essential. Your bird will destroy your house and be very dangerous on the floor.
Your (older) kids and girlfriend can have a working relationship with him through target training. When he touches the chopstick with his beak, he gets a treat. It's a way for them to build trust without having to touch. My three year old target trains Chipper every day, and I hand him the treat.
Please read everything you can get your hands on. We're working with a behaviorist as well, and it's so helpful. Remember... No floor time, no cuddling, no petting down the back, under the wings, no nesting behavior inside boxes, etc. Post every question you can think of, there is a wealth of knowledge here and you owe it to your bird to educate yourself and give him a proper life!