(Re lyric questions: "grat" = "greeted", which means cried or yelled. She's yelling and spitting rather than giving in.

"Weary fa' you" is just another generic curse: "God damn you/Woe upon ye/Ill betide you/De'il tak ye"; the woman who came in with the clothes in the morning is cursing Willie for not forcing Eppie, because if he'd succeeded, Eppie might have "hired his hand," which I presume means "paid to be married to him."

Eppie is NOT the one who's complaining about his lack of force. And I suspect that if the song were intended to show that he should have been more forceful, it would end with Eppie being defeated or punished (by man or God) rather than riding away.