My 4 year old son

Hi we are currently waiting for our son to be referred to paediatrics 

but I would like some advice to help cope with his behaviour and to see if he's like other diagnosed children 

he's never slept well Evan as a baby,he wakes early and is constantly on the go 15/16 hours a day,he rarely sleeps through the night and often wakes during the night for long periods 

he gets obsessed with certain things.toys that rotate,spiders,human body He loves watching about them on YouTube ! In fact that's the only time we can get him to stay still for longer than 5 mins ...from the age of about 18 months he became fixated with his dad   and it's getting worse as he gets older 

he will chat to anybody he goes into great detail and will get toys to demonstrate,he speech has always been very very good and from a early age he used words that amazed us

he will play with others but has to be on his terms they have to do and play with what he tells them and he's very vocal in his demands if his rules are not followed he will become angry and will scream/cry and lash out 

He will only use the black handled cutlery,he looks in car windows to check the steering wheel is in position he likes,DVDs have to be put in box the way he likes 

He often has meltdowns for no real reason and they can last for hours a big one the other day was because his dad didn't explain something exactly as he wanted him to

he will scream cry throw stuff hit and kick this can happen 4/5 times a day 

he has 3 older siblings and 1 younger and he's hurt all of them and he also irritates them with his constant demands

he can also be a very sweet loving boy and I've been sayong for nearly 3 years something's not right,I just do t know what to do to help