I don't see why that would be an issue. You may want to consider the restaurant area upstairs and towards the back. It may be more suited for your needs.
You can certainly go there. They can make virgin drinks upon request. (no alcohol) I would call ahead of time and see if they do anything special for birthdays.
There's a division between bar and restaurant. I'm sure there'll be no problems.
Thanks! Your answer is awaiting moderation.