I think that maybe something in his IEP about shoes might be called for. I remember being so uncomfortable with various clothing items that it certainly interfered with MY learning. and I was not as severe as he sounds.
I would take him and try ALL sorts of shoes/slippers at the shoe store (s). ALWAYS make sure they fit - with thank you I never ever know if his shoes are too small. He only says his legs hurt. After years of this he still doesn't clue in to leg ache = shoes too small.
Does he receive brushing therapy? With thank you we found he is much more able to tolerate a LOT of things after just a few weeks on the brushing. If he has an Occupational Therapist (OT), the Occupational Therapist (OT) should be able to teach you this. At first the brushing should be every 2 hours or so - even during school. The payoff for school is that it makes many kids much more relaxed after. And it takes about 2 minutes. Teachers and aides can easily learn it.
Would crocs work? They hurt a lot less when thrown. I prefer the brand name, other people find other brands work better for them. Some are softer than others.
Does the afterschool program provide snacks? Maybe your child needs to be given more of a snack. They may give you the "not fair to everyone else" spiel. That is why kids are individuals. If no snack, or the snack is not enough, pack something for after school. Or see if they will able to let you send in a big box of something for the week and have them store it. That way if he is super hungry they can give him more and then let you know he is out early.
Hungry makes so many kids act out. So do sugar (or too much sugar) food coloring, preservatives, additives, etc.... Like Dude and the others, my difficult child is mean, even vicious, if he gets too much sugar or sugar on an empty stomach.
Is there something other than fruit rolls that he likes? Or can you get fruit rolls at the health food store, the ones with-o the extra sugar and food color? We had a lot of trouble with these. With difficult child I used a dehydrator and made fruit rollups (puree fresh or froz fruit and spread on wax paper cut to fit the tray - let sit for a few days).
As for the wallpaper - was it coming loose? MANY kids will pick at wallpaper with a seam that is coming loose (including mine). Yes, it is a good idea to teach him not to do this. Yes, you do get into trouble for this. BUT the school should NOT have wallpaper that isn't sealed tightly because one source of lead poisioning in kids is from wallpaper pulling paint off when it peels. (Not sure this is relevant in your case, but it could be ammo if they are over-harsh with your son.)
They should have extra wallpaper. Or maybe you can provide a poster of a work of art to put over the spot where he peeled the wallpaper off.
Sorry it was such a tough day.
Susie