Why JimmyJackSteve? Because he's an essential element to the show, the character that simultaneously lifts Fiona up while pulling her down. They were able to get by for one season without him, but it was always obvious that he was coming back - otherwise, you would have seem him actually get whacked.

No way. Frank is irredeemable. That's a fundamental part of his personality. And it's TV, so he'll be able to just go on being a drunk, albeit with a new liver.

Undercovers don't break people's fingers. More likely the father put Jimmy to work in semi-slavery in South America to recoup some of what his daughter's arrest cost him, and Jimmy got his freedom when fate finally caught up with Daddy.