Unfortunately, you are not able to ask multiple questions on enotes, so I have had to edit your question down to one question which I will respond to.

We are told Molly's plan at the beginning of Chapter 12. Interestingly, whilst her husband is courting another woman, Nancy, at the party, Godfrey's opium-addicted wife has something else entirely on her mind. It is important to note how these two scenes are juxtaposed, or contrasted. Whilst Godfrey is doing his best to forget about Molly, Molly is trying to ensure that nobody will forget about her:

The journey on New Year's Eve was a premeditated act of vengeance which she had kept in her heart ever since Godfrey, in a fit of passion, had told her he would sooner die than acknowledge her as his wife. there would be a great party at the Red House on New Year's Eve, she knew: her husband would be smiling and smiling upon, hiding her existence in the darkest corner of his heart. But she would mar his pleasure: she would go in her dingy rags, with her faded face, once as handsome as the best, with her little child that had its father's hair and eyes, and disclose herself to the Squire as his eldest son's wife.

Therefore we can see that Molly's desperate plan is to turn up to the party with child in tow and publicly denounce Godfrey and reveal her connection with him and his legitimate child. Of course, as we discover, this does not all go to plan.