Red-ring is usually caused by dust and stuff in the console. Clean your electronics.
Not necessary, it significates a hardware error.Quite a more "brutal" BSoD.
I've had my xbox for 3 years and the only time I've RRoD'd is when I had a really screwed up copy of mercs 2 and when I played it nonstop for like days(wasn't playing it most of the time but it was on).