These are some great ideas.
I think I will try to work with the school on a gradual plan or at least leave it semi-opened to see how the first visit into first will go. I think after my DS will see that there are children just like him and everything has similar format, he will fit right in without any troubles. I like the idea of the goodbye party, which would substitute DS's birthday party in K. If the K teacher would be willing to let DS to come back from 1st to tell other kids how it is, and it ways it is different and it what ways it is the same, that would be great also. I am thinking (but it will me more on DS to decide) that he will implement similar plan to greed the K teacher in the morning (it is on the way to first anyway).
The great thing is that the gifted teacher has pulled out DS for gifted enrichment with the first graders from his future first grade. So they already know each other.
I will keep my eyes open on art and other specials. In last two weeks it seems that DS is all over the school being pulled out with higher grades, that his base K is really just a base for lunch, recess and center time (where he has his own projects anyway, but is in the same classroom). So I am hoping that the process will be easier than it seemed two weeks ago. I am just flabbergasted how easily is DS working on math along side 3rd graders, and so forth. I think he is understanding the school now more, and becoming more flexible.
We are meeting with the school this afternoon, and I am so thankful for all these replies, which gave me ideas how to approach this whole skip. Thank you all.
I will post update how it is going.