Again sorry you are here, but I agree it is a good place to vent, and ask advice.
Also, can you update your "signature" in your profile to list your age and your wifes age as well as length of the relationship and the marriage?
First you need to take your focus off of her, and look at what things you can do to improve yourself - make yourself happy (GAL).
You need to detach (really difficult when you live together) make her curious, make her pursue you. Avoid any further R talk unless it is initiated by her. Even if/when this occurs avoid be argumentative by listening and validating what she says (not simply agreeing with her - let her know you hear her and understand what she is saying)
As for your questions:
1. I think you should say nothing, you already expressed to her that you don't want this "scumbag" around your kids.
2. I would make the calls, but not advise her of the results immediately. As I am starting to find in my R, it's not always bad thing to "go along" with their plans. It may actually cause them to doubt themselves.
3. It seems obvious to me that she did cheat based on what you described, but it's only as relevant if that is a "boundry" that you cannot get passed. Is it a deal breaker for you if she cheated or can you get past it and forgive her?
4. As long as she lives with you, I would advise her that you don't approve of her carrying on any extra-marital R's. I think you already told her that. I don't care "what she thinks" though, about the fact that she is done.
5. Don't worry about it now.
BITS SIC
Me - 34 W - 33 M - 8 years T - 15 years D7, D5, D2 Bomb Nov 10/2010 "I'm not happy and INILWY" W Staying for the kids Mar 13/2011