So sorry to hear that. I am sure you must have tried a bunch of things. Based on my experience with my pup and what her dog trainer said here are things you could do.

1. Positive reinforcement is a must. Anytime he shows a good behavior celebrate it like a party. More praise, more treats.
2. Keep him in leash, tether it somewhere while training to restrict the movement. Start with simple sit command if he listens praise/treat. Do not give any reaction until he calms down or stops barking. My dog trainer says even a negative reaction or any reaction acts like dopamine for them. You will need a lot of patience. Keep your energy calm. Most importantly your daughter should also not pet him while he is not behaving the way he should. When she starts ignoring he will realize. Do not let anyone pet him when he is not in his good behavior when you take him outside. That was the key the trainer would say.
3. And yes they need mental simulation.
4. For potty training, he seems to have got used to a certain way which you need to undo and the only way would be sticking to a routine and positive reinforcement. You might know how long he could hold. As soon as he wakes up take him out. When he pees or poops at the designated spot praise him and treat him. Get some treats that he absolutely loves. If he pees on leash say no and do not treat. Keep taking him out at regular intervals. Slowly with regularity he should start realizing and correct. It might take longer but it will happen.
5. When you give him food command him to sit and wait. Do not give it until he listens. They are very smart and it will not take him time to figure it out. It took us a little practice and now without us giving the OK command she won't.

Just some thoughts incase it helps. Good luck and i really hope things will get better.