"Interrupting
Consistently not doing as asked
Saying awful things about people
Aggression
Hitting
Throwing things in temper
Shouting
Always has to win whether it being in a game, disagreement ect"
I could have written this list about my own 5yo DS. It's hard. I think his behaviour is not as extreme as you describe, perhaps because we do implement consequences. But it's challenging every single day and he never ceases to push the boundaries. I am beginning to suspect he may have ADD - certainly some of the techniques recommended for ADD kids are helpful with him.
What works (mostly) for us:
We have a clear, short list of behaviour rules. No hitting, no shouting, no name-calling, no pulling clothes etc. He knows them well. If he does it, he gets max one warning then the consequence. Usually losing bedtime story/ TV time/ Lego. I also avoid time out unless it's REALLY bad, because he's the size of a 7yo and dragging him to his room sets a bad example IMO.
We also have a list of good behaviour, like helping his siblings, tidying up, doing as we ask first time. If he does these unprompted, we give him a reward for his 'star jar' which he can trade in for stories/ treats/ days out even if he earns enough. So he always has a way to earn back lost privileges.
It's not perfect but it keeps his behaviour from getting out of control. I also talk to him about any issues at bedtime when he's generally calmer, reassure him that we love him and ensure that we are clear that the behaviour is bad, not the person, and HE has the power to change it. Every night he promises to try harder the next day - and ok it doesn't always turn out better, but he feels motivated to try.
You may find school is helpful, with the routine and discipline. My son behaves better for his teacher than he does at home!
I do think anxiety is the root of some of the issues, especially his reluctance to go out (whenever we suggest any activity, his first response is generally 'No!' even when we know he'll enjoy it.). He has a huge need to control what is happening. As pp said, giving advance warning or a choice over some aspect (shall we go by bus or metro?) helps.
Sending a big un-Mumsnet hug because I know how hard this kind of behaviour is. I've spent way too long on Google, I'm kind of hoping it's just immaturity but ... if it's not then I hope boundaries and consequences will help him work on his own self-control.
He's also a very intelligent, funny, loving child - it frustrates me so much that he cannot control his negative impulses. But I am trying to learn and work with him, find a path that helps him and ease our family life.