Stay hopeful, I think there is hope in your situation. That said, most people are going to think you are nuts for fighting for your marriage/reconciliation. However, you are not. I think it is honorable for you to be on a quest to reconcile your marriage and win your family back. That said, this journey is going to be rough and at times things are going to look nebulous. But you seem determine to do what is necessary to make things right.
I might be wrong, but it sounds like your wife might still be hurt about what you did and is still trying to heal. Her being difficult is mostly likely her just trying to protect herself and her way of expressing that she is anger and hurt of what has happened. However, when she is being difficult, that is a great opportunity to demonstrate your character, your ability to listen and validate, etc. Could you elaborate more on how she is verbally peppering you? If she can see you keep your cool and showing understanding when she is being rough, that will speak volumes, every though she might not say anything, she will notice.
I will try to get to your questions later as it is really late here in Boston right now. If you haven't read divorce busting, I would pick up that book. Also, I would read other people's story on this forum. The more information you have, the better prepared you will be. I see a lot of good things in your situation. The mere fact that she invites you over says a lot. The key is for her to see your changes and that those changes are consistent. I will talk to you later.
