Is there any specific criteria/guidelines for what disqualifies something from getting featured on the front page?

For example, if I write an article and I include any form of nsfw content, is that automatic grounds to ensure that article will never see the front page?

Generally NSFW is less likely to get featured on the front page as viewing NSFW is an "opt-in" feature available upon when someone creates their account. A user has to consent to viewing NSFW. Although with the addition of Buzz, I did see a feature allowing you to spend buzz to promote your content to the front page. So maybe there's a chance.