I agree with Exbury on your other thread - I would suggest that he is bored at nursery, the children thre are no real companions for him as he is intellectually ahead of them, whatever his emotional state. I am not surprised he won't sit still at group time if it is basic stuff that bores him.
My ds (Nov 02 baby) was exactly the same when he started at nursery which put them into their 'year groups' rather than '3-5' groups. He then suddenly became in a group of children younger then him, less advanced (I have a dd not much older than him and he copies her) and not emotionally able to communicate on his level.
They were learning to look at a picture of a fish and realise it was a fish (increasing vocabulary) whereas he was teaching himslef to read fish at just 3. He went through the same frustration, clinginess etc at home, altho at nursery they say he was fine!!
Luckily we were able to do the same as Exbury and he is now in Reception and thriving.
Is there any way you can expand his interests at home? My dd is learning the piano and really loves it, plus they both swim, and do football at weekends.
If you can get some simple reading books (as he is already writing things like 'chocolate' and 'I love you') then he could learn to read. I found the Jolly Phonics DVD and finger phonics books excellent - I had them for dd and ds just used to watch and follow too, but as there was no pressure he felt like he was playing. Once they can read, they then read books for pleasure and it is amazing what they can pick up - my dd lokes non fiction books so we have the set of Dorling Kindersley Eyewonder with loads of fascinating facts, and also the Kingfisher Young knowledge. Ds loves them too and they really enjoy 'telling' me some new fact!
Also is there anywhere you could take him in the afternoons where there may be older children for him to interact with - if he is the oldest in nursery it must be hard for him.
I would go with all the help that they are offering you, but make sure you have a great deal of input and the IEP is shaped the way you think is best. If you try working with him on things to keep his active brain happy, tell them what keeps him interested and make sure they do it - I had a comment that they 'were not allowed' to let ds have books to read at nursery!!!!!
Any 'work' you can do at home will also help as he will be happier to 'play' in nursery or learn from their topics. My dd is Year 1 still loves working at home and we reguallry do Jolly Grammar and maths work way ahead of the school work; she is happy with this as it keeps her progressing as she wants to and means she can enjoy the topic work and extend her knowledge from that. We often go on the interenet and expand on these, and when she takes this back into shcool to show her teqacher the praise helps her self confidence as her perfectionist streak shows itslef in lack of confidence in group situations, particualry with adults!!
Take it slow and steady and celebrate all successes - a real problem with these children is their brain is way ahead of their physical abilities hence the anxiousness about getting it right, so all your praise for what they do well really helps with this. I am sure you know this but it is good to praise what they do eg "you really concentrated hard on forming that 'l' correctly" (even if the result is appallling lol), or 'I am so pleased that you tried your best with that XXX' so they begin to understand what is required in class. Lots of cutting and sticking and colouring (if he likes that) can hone fine motor skills for writing and phonics will help with reading and spelling. Ther eare plenty of basic maths books around too if he likes that.
Also i am afraid you need to be prepared for Reception year to be a difficult one unless you can sort out the intellectual needs / companionship issue as it is not until Year 1 that a lot of these children really get the higher level work they need to keep them fulfilled.
I imagine now I will get lots of comments about 'hothousing' but I am not advocating that at all - just keeping his active brain properly fed with what it needs to enable him to concentrate on being a happy little boy.
I wish you the best of luck and hope it all works out.
PS apologies it is rather long