1) I don't think this is necessarily true, although if someone makes a habit out of cheating, I doubt it would be wise to trust them.
2) This question is pretty subjective. I consider cheating to be a physical act, but extramarital emotional attachments can be formed that undermine a relationship more intensely than simple sex can.
3) It's possible he may outgrow it, but unlikely. At least, not in the relationship with the woman who has consistently forgiven him for his misdeeds. Why should he change when it's not a deal-breaker for her?
4) I've been told that men (that are the cheating type) only need the opportunity, while women need a reason.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?