Congratulations on your first open water event!
Swimming near other people in races like that is challenging. I usually try to line up on the outside edge of the course where there may be a little room. I have been kicked (by accident) during race starts. It does get easier the more you do it. Your description of the "bag of worms" is exactly how it feels!
What I like about open water is that you never hit a wall--you can just go and go. It's a great way to really practice kaizen and get a good feel for different parts of your stroke.