We have ours in the classroom, chairs in corridor where you sit till you are called in. You cannot hear what is being said.
List on the door of who is in at what time, clock on the desk so the teacher doesn't run over.
Given 3 objectives to work towards, so ds2 who is now in yr 1, was given in reception, to get some of his letters and numbers the right way round, improve presentation and something else.
Ours are 4pm - 7pm and the child comes too, it is actively encouraged. Ds1 who is in year 4 will choose his 3 objective goals, from a list of 3 or more.
Re inviting someone for tea, I was confused when I saw my friend in the playground for pick up as I knew her son was going to another child's house for tea, she came to collect his book bag from him. I asked her why and she told me that the mother of the other child looks through book bags to see what level the invited child is on 
I volunteer in school, it is fine to look at the display boards, totally not fine to look through another child's folder
I put up displays, depending on the size of the work we showcase everyone, or we showcase the best, the middle and the bottom, a nice broad spectrum of work.
Re the competitive Mums, laugh it off, seriously, lots of parents lie about how well their child is doing. If little Jacinta is in gifted and talented at 5 doesn't mean she won't wind up dropping out of school at 14 to go and drink and smoke by the local shops
Concern yourself with whether your child is happy, and making progress.