Hello, I'm a mother of a former wanderer myself. Lots of different things can cause some of what you mention including normal immaturity. There are other things to consider as well.
Sometimes I feel like a broken record here---- but so often, kids that sound very much like mine mystify their parents and schools. So, I always want to share our story in case it might help. My son has sensory integration (sometimes called processing) disorder. It involves the nervous system and is a developmental delay. Before you say---- not my son, he's not delayed! . . . let me tell you that my son is very smart and academically usually above but at least always at where his peers are. He also met all developmental milestones on time . . . in fact, I wasn't aware of a problem until he started attending preschool. He was a wanderer there. He had great difficulty in circle time, had some peer interaction that was not great, and would resist various activities (especially writing).
Sensory can affect how the brain organizes itself to do things. You see a room, a lot is going on (and Montessori is usually set up in stations, right? )----there is a lot of noise, visually it is very stimulating, and it can overwhelm a child's nervous system. At that point, a child has a trouble focasing on any one thing. Hense, they wander. Working independently is important at some point--- and that time is coming soon for your son. So, it is wonderful he has one on one attention, but I am sure that getting him to the point of sitting and working by himself is a goal. All developmental delays such as sensory or add/adhd have a high rate of dyslexia along with it too.
Sensory issues can also be mild enough that a child has a hard time functioning in a classroom but not obvious enough that those around the child know exactly what is going on. It is treated with occupational therapy (who diagnosis it) and this is like play therapy. They do work on things like hand writing as such fine motor tasks are sometimes difficult for a sensory kid. My son had trouble---- so he avoided it. He is now in kindergarten and has been working on it since he was 4.5 and is doing just fine now.
Birthday parties are notoriously hard for many kids. We've had some bad moments outselves. I have two boys---- one with sensory who just turned 6 and one who does NOT have sensory that is 4. Both get overexcited and have done something a little over the top at parties. But my sensory kid has a harder time.
Your child does NOT sound autistic to me. Not even aspergers which is high funcitoning.
Circle time ideas that worked for my son . . . well, first---- my son needs movement to focas. We do tons of things before and after school. At school---- he may do some things like jump up and down, wall push ups, do some animal walks, etc. before there is a time in which he had to sit with the group. Also, giving choices really helps. Kids like mine need to feel a little bit in control of their enviroment--- so his teacher would ask him if he was getting restless or resisted the circle all together---- would you like to sit here beside XX, would you like to pull up a chair outside the group, or would you like to sit on Mrs. XX's lap? He'd pick and then inclined to follow through.
For figuring out what is going on . . . I would say if the school has a social worker or psychologist---- this is excellent. They are used to dealing with kids and can give you unbiased information of where your child is having issues. In terms of other people I would see, I am thinking an occupational therapist would be excellent for your son. If I thought my child may have add/adhd---- I would seek out the help of a child psychiatrist. If I was concerned about autism, a developmental specialist--- often a center or children's hospital has this. Psychologists are helpful at times depending on experience. Okay . . . I am one. I admit it. But I didn't specialize in children. I would not be helpful to you. In conjunction with a school, I think they are fantastic. Working with a psychiatrist on a diagnosed problem, they can be helpful too. But it is like anything else, you need one that knows there stuff and has proven over time that they are kids and their families. Also, keeping your pediatrician or family doctor in the loop is wise and they may have suggestions of where to go. (you also probably need a referel)
Anyway, to make a long post even longer---- I will tell you that my son had issue after issue in preschool. We got a sensory diagnosis which was the right one for my son---- and he is now functioning very well in kindergarten. He takes no medication as this is not helpful with sensory. There is Not one concern from his teacher and he has no IEP. I've tried a variety of things from all different types of disorders and work hard on addressing his nervous system. So whether you have a diagnosis or not, try different things to help and see if any work. I have lots of sensory ideas if you would like any. Good luck, it is definately hard work guiding a child through it all. (and keeping your sanity during the process!!)
this is tough. My son used to hit me when he was angry too and it's not good. He's doing it a lot less now. He's five. Sounds like he does not know how to deal with his anger very well.
I would contact your pediatrician.
Also, isn't Montessori less structured? Maybe he needs a more structured environment iwth more predicable routines.
At four my son struggled to do circle time, I think a lot of kids do and sometimes he will make noises in it like sirens, he's five. My son still does not like circle time.
He sounds VERY smart. I would not put so much pressure on him to perform, just let him relax more. I think kids are pushed too much these days. It is a hard balance.
He does not sound autistic to me. DOes he relate well with other kids.
Make sure you got a reputable psychologist, sorry but I don't trust all those guys. If you really think he's got a problem, maybe seek out an actual MD or psychiatrist.