What can I do to help my son prepare for kindergarten next month?

My son will be starting Kindergarten next month and he is starting to ask more questions about it and I want to help prepare him for it. I don't like his school or their rules but I don't really have a choice. He now understands that he will be going alone (no mom or grandma) but he doesn't understand it is for seven hours a day. They do not offer part day kindergarten. How do I prepare him for the "big boys" room since they do not have one in the clroom, prepare him for the cafeteria where all the grades are eating (he is a bit of a slow eater), etc. The big thing for me is how do I get him to stop saying what he already knows? He got interested in school when he was 3 and we have been doing workbooks ever since. He is finishing the second grade workbooks (his writing isn't that high though). He was denied pre-K in this school because he spoke English and already knew how to read. His school is primarily Spanish speaking with questionable recess supervision. When I asked the principal why there were so few supervisors I was informed that kids need to learn their place amongst the other kids (some kids are bullies and some kids are bullied). I have seen fist fights taking place right behind the "supervisors" and no one stops it. I want him to have the best experience he can but I hate their rules. I cannot escort him to cl, they do not have kindergarten orientation, I am not allowed to phone the teacher and leave a message, I am not allowed to visit his clroom, I just have a bad feeling about this school (I mean why no parental involvement?) but I cannot homeschool him and I do think he needs to be with other kids. What is the best way to prepare him for it?