There's an upvote feature on HN exactly for burying stories that are irrelevant. If enough people have voted this to the front page, it simply means that enough people find it relevant. If it's not relevant to you, you can just ignore it.
2) I refuse to downvote anything except comments that include "I'm going to get downvoted for this...". The signal is too noisy to figure out what a downvote means.
