That sounds really hard on him. Sounds like they have plans to deal with a child who has x,y, and z wrong but the reality of the child and his own personality and specific behaviours has them flummoxed.
The bullying has to stop especially as your DS can't cope and fights back. Rather than blaming him for fighting back, could the school not give him some private space for time-out where he could be alone for 5 minutes. It makes you totally sick, doesn't it, when you know your child was simply protecting themselves and the school say they are equally to blame. Happened to my DS a couple of times. I actually saw one event as we live next door to the infants school and I saw the child holding DS by the shoulders trying repeatedly to kick him. DS was trying to get away and struggling but according to the school he was equally to blame. .
I am not sure about pairing him up with another child with sn either. Does he need to be paired with anybody at the moment, until he has settled in?
Only a suggestion but what about drawing up a list of things that DS does or needs to give to the teacher. I am sure you have talked to her but now she has had the chance to get to know him maybe it would help to make a list of his particular behaviours, their triggers and the ways you have of dealing with them so that she has strategies to try. A long time ago I saw something like this on a website but I have no idea where now. I will try and have a look later - it might have been the NAS website. It's all very well them giving you lists of things they are going to do for him but if they don't understand your DS it isn't much use.
Does he have any one-to-one time with anybody? Is he getting any therapy?
As for the tie thing - that is petty. Don't they have a spare they can lend him? Surely they know, if he is anything like my ds, that he has trouble organising himself and keeping his things under control and he is going to need some help in the beginning. They should cut some slack.
Sorry I can't offer any real suggestions only sympathy. I think you need to go to the school and talk to them and make sure they know what they need to do. Talk to the head teacher too and find out what she observed - maybe she can help the teacher deal with him in a more constructive way.