The final team Argentina, Iceland or Nigeria. It feels like a toss up. Nigeria is in with a win and have a chance with a draw but Argentina will come firing for many goals. Iceland play a resting Croatia and the goals they'll need depend on the other game.
Not even. Argentina need a Win + Iceland lose/draw. OR Win by 2+ goals more than Iceland does OR Win by 1 goal more than Iceland does while scoring more total goals than Iceland as well OR Win by 1 goal more than Iceland while scoring the same amount of goals as Iceland and winning the draw vs Iceland
EDIT on the last point. If it was the last scenario the Iceland is way up on the disciplinary tiebreakers so unless they get a bunch of cards then Iceland is through there.
They will rest or sure, especially after that last result. Croatia ins't as worried about Nigeria winning the group.