Not in my experience. Multiple submissions (non Show HN) of mine have been second chanced. I can't be certain, but I don't think any of my Shows have been... I guess that says more about the content I create than the content I share.

Nope. If you email [email protected] with the subject "second chance pool" and it is not your submission, there is a very high chance one of the lovely mods will take the submission and second-chance it.

Often enough, they even email the original authors and submissions about it if it is a really good submission!