There is three official referees, one running on the field and one on each sideline. They do have a reserve/4th ref who is out of the field. Currently there is an experiment with an extra referee...
11 per team in the pros, but younger it can be 6, 8, or 11 per team
There are no squares on a soccer field. There are, however, rectangles.
There are over 6,000 soccer fields in the world. This is only including in the soccer fields in Europe.