we are also trying for a grade skip into k. it is like beating my head against a brick wall sometimes....but we are pushing forward. i think anything you can gather before a meeting is great- any testing, any work samples, books she has read, etc. i did NOT bring in worksheets for the same reason you said...i did not want it to appear like i was hothousing him (which i am not) and so i brought things he had done on his own- stories he had written, summaries of books he had read, several books he had just finished, i video taped him reading one of them, and a copy of his educational and intelligence testing. the things i brought in WOW'd the principal. she said she was not a proponent of grade skipping and was set to tell us that, until we showed her what he was doing....then she wanted to put him in first grade! lol. socially he really can't go above k, so that is what she is fighting with us for. ((i would personally just bring the samples with me on the day of the meeting and be prepared to leave them there. that way if they have any questions about what you brought you will be there to address them, instead of them making assumptions. i have a feeling if i would have dropped of my son's work samples off first they would have assumed he had help...but since i was in the room when they saw them for the first time, i was able to talk about when he wrote it and answer questions about things he could do on his own. our principal asked to follow up with us after our initial meeting....i liked that.....bc then she had our work samples and our arguments AND then went away to ask advice and ponder our evidence.))
i did not find a ton about little kid acceleration but i did read a nation deceived and the iowa acceleration scale. there where things that applied to my child in both books. basically what i picked up was that k was a good time for a jump for the right kid and that acceleration can be a positive experience for a child. there are also a few articles i was able to find online by googling things like early admission to kindergarten.
i understand what you say about first....academically my son would do better there as well....but i am willing to send him just one year ahead to k IF they make accommodations in the class. they will do this if i can manage to get him an iep...which i am working on(it is a battle). if for some reason they would allow him to skip to k, but with no accommodations...so he would then spend the entire day relearning the alphabet (and he just now walked past me with a 2nd grade chapter book in his hands he devoured in about an hour)...i would not do it. i'd homeschool him. here if you homeschool for k, you have to homeschool for first. if you try to put them in school after homeschooling k, they make the child repeat k. so it is a 2 year commitment on my part. i am a teacher by trade...so it would not be completely out of my element...but i am not trained to teach gifted children and really am unsure of how to meet his needs.
i agree that the process is frustrating.....but like you i am also thankful for the opportunity. i kind of feel like it is my duty to fight for him. i know in my heart that the thing i can NOT do is just wait a year until he meets the k cut off, and then send him to school like a typical kid. that would be a great disservice to him. he is far from typical. i have a feeling this will end with me in the superintendent's office. lol....but i have promised myself that if i am homeschooling him next year....it will be because i ran out of people to appeal to.

good luck!