Well, since Le Pen is gone and there's no other options obviously Melenchon. In the real life I'm "rooting" for Hollande and hoping for FN gains at parliamentary level, for reasons that should be pretty obvious.
IRL it'd be emigration for me if France had sunk to that level, but anyways I'd expect you at least to realize that Communists are bad news and should never be supported in any circumstance.
Ordinarily not, but if it got to that point a nihilist approach might be appropriate. Want to get them run out? Give the lunatics what they want. As for real life Hollande winning would probably be for the best because it would put the mainstream right into disarray and allow for the "far right" to continue to make gains from their weakness.