So...I'm wondering if you can spare some time to volunteer in the classroom? I work from home, so I am able and I have really learned alot about all the kids in DD's classes. These sorts of issues are part of the reason I decided to NOT move our DD8 to a different school with a seperate GT class. People don't live in bubbles, you meet all kinds of people all the time.
In our case, my DD is all about her PERSONAL SPACE and of course one of the boys is very physical and it's like they are MAGNETS! ugh! The more she tried to ignore him, the more he wanted her attention. It wasn't a HUGE issue most of the time though, she didn't sit by him...this year he is in the other class, but we have a different boy with other issues...and so it goes.
At our school, kids who have things like you are describing (throwing chairs vs just crying/pouting) have IEPs and usually an aide as well, so if it's that sort of issue, they are often allowed to go outside for a bit. One of DD's classmates has ODD so he has a one on one aide. I saw him have a breakdown last year when another staff had to carry him out of the classroom and I was surprised when I saw it, I'd never seen him like that. He's on medication now and is much better...
And you can't really go to the teacher and ask specifically about W's problems...but you could try to get into the classroom a few times and size up the situation for yourself.
Oh and I did ask for a seperate desk for my DD, but she is the one who wanted that...
