Yes, Edmund is attracted to Mary's liveliness. The recent liveliness Edmund enjoyed was engaging in the acting which he had so wholly disapproved of a couple of chapters before. It's a testament to how far he really is gone.

As you alluded, Fanny is only human and she had ranges of feelings during that whole acting period, ranging from jealousy to feeling left out to almost wishing she had had accepted the part instead of Mrs. Grant.
But reflection brought better feelings, and shewed her that Mrs. Grant was entitled to respect, which could never have belonged to her; and that, had she received even the greatest, she could never have been easy in joining a scheme which, considering only her uncle, she must condemn altogether.

She's relieved that it's all over for her own sake, but her overriding concern has always been for the others. The word agenda implies that she has some control of the goings-on or some aims to accomplish. Her only control is of her own reactions to what happens around her. She has no illusions that Edmund's suddenly spending less time with Mary will benefit her somehow.
ch 21 "After a little while, I dare say, we shall be meeting again in the same sort of way, allowing for the difference of the time of year.”

She always listens patiently as Edmund waxes on about how wonderful Mary is.
Fanny could have said a great deal, but it was safer to say nothing, and leave untouched all Miss Crawford’s resources— her accomplishments, her spirits, her importance, her friends, lest it should betray her into any observations seemingly unhandsome. Miss Crawford’s kind opinion of herself deserved at least a grateful forbearance, and she began to talk of something else.