It sounds to me like you and DAD haven't been firm or consistent enough a the onsets of these behaviors. Kids will do these things, and it takes total diligence to not let them form the habits or teach them not to.
I agree none of these behaviors sound autistic, but I strongly disagree that you should start tolerating and setting good examples ONLY without more discipline. Yes, of course you need positive reinforcement and to set a good example, but without firm consistent discipline for misehavior, it will not click.
He wouldn't be asking a million times after you say no if you do not allow it. As in, "That's enough junior, please do not ask that question again." Then consequence if he does. It's only tough at first, he will learn and become much easier to get along with. It's not better to keep letting him interrupt etc.
Examine what REALLY happens in a discipline situation. I just talked to my friend today-whose son acts just like this, and she's baffled why my kids don't, because she's even harder on him than we are on ours. Of course she thinks ours are just easy, but it's because we don't allow it.
I've spent lots of time in her house, she is not consistent and actually lets her own discipline be stepped on a canceled out. For instance, if, after she has ignored him for a while, then warned him 10 times to stop doing something (first mistake, ignoring and a million warnings), he doesn't, so she smacks him, threatens him, puts him in time out, yells at him or sends him to his room or whatever (inconsistent results-problem#2) He then gives HER a consequence by insutling her, calling her names, coming out of his room when she told him to stay, you name it. Then she looks at me like, "See, what can I do? Nothing works!" HELLO! He just punished you for giving him a consequence, the battle is not over!
Our kids got ( I say got, because this really doesn't happen anymore) one calm warning for something, a firm consequence on the SECOND calm warning, and if they were to react negatively to it with insults or further tantrums aside from normal crying (which they never have-and normal crying is allowed of course) that is where their lesson would BEGIN. Which is why they don't do it. All their rules are CLEAR, and they know a consequence is only the result of THEIR behavior, not our anger, therefore, re-offending by bucking the discipline would be a fresh new offense.
Therefore, even though we are technically "tougher" than her, she is punishing her son way more, and always angrier, while ours hardly ever need discipline. Similarly, we would have never defied pour parents after a consequence was doled. Did that make us miserable kids? No, it made us happy kids with rare discipline. Kids are very smart, and if you use positivity and love 99% of the time, and firm discipline when they choose wrong behavior, you will conquer this.
You sound worn out and like you're ready to blame a disorder. I think you need to take a deep breath, believe in this child, improve his positive time, give him some new responsibilities, lots of rough play and fresh air, healthy food, make sure dad spends a lot of quality time with him and FIRM UP as well as TONE DOWN the discipline. Less is more. Clear rules, immediate firm consequences.
When my daughter starts talking non stop and firing off questions while I'm trying to do the bills or something, I say respectfully, before I'm annoyed, "Sweetie, I can't talk right now, I have to do this." That's all it takes. She goes and plays. Because she's an easy child? No. Because she's terrified of me? No. Because consistently form birth, we enforce what we say. She feels secure knowing what's allowed. She knows not to continue something I have told her to stop, she's proud that she knows it, and more importantly, she knows I will come play with her as soon as I can, because I do. She get endless positive support and love every day. Little bro, same thing. Kids don't choose negative attention over positive when they know the choice is real.
Why is he allowed to still play video games if that's how he acts afterword? What is his consequence for refusing to go to bed? Being impolite about gifts? Tantrums? Refusing naps? Being a sore loser? Using the same firm thing every time for everything right away as it starts will stop this.
Things are off the rails, but you can improve them! If you want a good book recommendation, let me know. Take a deep breath. You can do it! Dad needs to step up too.