A red card, or ejection
They are technically called assistant referees.
They were previously called Linesmen, now they are officially called Assistant Referees, or Referee's Assistants.
3 referees are in soccer and football
Soccer referees are graded by levels, not by classes. Informally, a referee might be considered "Class A" if they are certified International referees.
If you're talking about soccer referees, I don not believe so.
red or yellow
The answer is obviously. Yes.