Advice on how to manage my 4.5year old?

Hi all, I have recently joined the community and am looking for some help, support, advice if possible. 

My 4.5 year old is currently under the consultant for suspected Autism.

As he doesn't have a diagnoses yet me and my husband are working very hard to understand his behaviours and "isms" and I wanted to speak to people who potentially have been through this or are going through it to see if they have experienced or are experiencing similar behaviours and how they are dealing with them.

Charlie has lots of little "isms" but the reason we are at this point is from a tremor he had 2 years ago and whilst this was being investigated the consultant asked us if he had any "obsessions" and at that time I hadn't paid any attention to them but then me and my husband realised he was obsessive over fans, irons, hoovers etc .... 2 years on and he has had a GARS test carried out and is scoring highly likely that he has some autistic traits. He is a very switched on, educated boy, fantastic communication skills. Where he struggles is building relationships with his peers. He seems to lack emotional understanding and has frequent episodes of hyper activity. He mimics films and applies words into day to day life but in the wrong context. He can often blurt our words very randomly and of no real sense. He over talks and doesn't respond to discipline. We have tried taking toys off him. Putting him in his room; explaining to him but nothing seems to work. He doesn't seem to understand when he has done something wrong. I can tell him off and he can laugh in my face and my husbands.

We also have an 8 year son and we have tried to explain to him that his brother doesn't always understand behaviours and unfortunately he can take the brunt of his brothers frustrations  which can come out in physical form or verbal aggression. 

Does anyone else have any thoughts, feelings on this? Is anyone else going through this or gone through this and has any advice on how to handle a child when he has one of his moments? How to get him to realise it's not acceptable behaviour. 

Me and my husband both feel like it's when he is overwhelmed with emotion and can't handle his feelings and then his behaviour deteriorates which is his way of expressing himself but we don't know how to respond in the correct way to get him to understand some of his actions and behaviours aren't right. 

Any help and advice greatly received.

Thank you :-) x