Hmmm, I think I would pull him up on every single incident as it happens. I would be very careful to keep the tone positive and authoritative. Think primary school teacher!
doesn't listen - bend down to his level and gently place a hand on his shoulder to get his attention. Kind smile. "I don't think you heard me earlier, the Lego needs to stay in the sitting room because Daddy is vacuuming the rest of the floors. How long do you think it will take you to move it all back to the sitting room?" Whatever you do don't move the Lego for him. Moving the Lego is the consequence of not listening. You can be kind and sympathetic but let him experience the consequence.
answers back - this might just be a bad habit so I'd try just pulling him up every time at first in case that works. In a calm but authoritative tone of voice; "Freddy that was rude. If I tell you to take something to your room it is ok to not be happy about it, but it is not ok to say ..."
bosses us all around - From his perspective this is the inverse situation of the one above. I think you need to be careful here as he is likely to copy the tone of your response when you 'boss' him around. Really important to play the calm, in control adult with this one! "YOU get my shoes!" "Freddy, that is not how you ask people to do something politely, would you like to try asking that again?" "PLEASE get my shoes!" "Are you saying you need help getting your shoes? They are in the shoe cupboard" "I'm BUSY" "no, we get our own shoes in this family" (walk away)
Talks over people - this does sound like ADHD! I would hold up a finger or some other hand signal and say "wait, we are talking" and continue what you were doing exactly as you were before, even if this means talking over him. When there is a suitable gap in the conversation ask him what he wanted to say. If it is not relevant tell him so and why.
calls people names - difficult to advise without knowing the names and context; are they personal and deliberately unkind or silly names that he thinks will make people laugh? You need a small reaction here as I would guess it's a reaction that he's after. "No, his name is Charlie" and move on. Every time. If you think he is being deliberately rude then you will need a consequence. The consequence should be immediate and linked to what he is doing. For example, if he insults you at home "I have asked you not to call me that but you have continued. I don't want to be in the kitchen with someone who is being rude to me. Either you leave the kitchen or I will. If I leave the kitchen you will have to wait for your sandwich" or "I know you were frustrated waiting your turn, but you know not to call people ... We will have to leave the playground now because you cannot call other children those names" or, when you can't remove yourself or him
from the situation "I don't want to talk to you when you are calling me names" Then refuse to engage in conversation beyond the basics that you need to get him to school or whatever. Keep your body language completely neutral like a teacher might. Kind but firm. You need to be careful not to accidentally teach him to sulk!