Punk Zombie cannot use Self Mutilation as a Slow to Die action. He can't even use it and select 0; any action that deals a fixed number of wounds that would reduce you to 0 cannot be taken, at all. It's not even a legal move, so if you tried it it'd be resolved like any other illegal move (can't happen). This rule is in the rules manual on the same page as it talks about wounds - I think it's page 44 but I'm pulling that out of the air, no book/pdf available at the moment.
Crooked Men: I'd go with 1.5 as Jewomie said but I don't think there's a huge distinction here. You're rarely going to see a model placed within 2" of the marker, unless you buried the model and you get to unbury it (Death Marshal's Pinebox, Wong's Three Demon Bag, etc).