ViralFuture

Definitely Twitter

you can do paid search and social media advertising, ie Google Adwords and Facebook Ads to get traffic. Your other option is to do organic seo and social media marketing which takes longer and is cheaper

definitely great for businesses, I've helped many businesses establish a presence on facebook and increase their sales as a result

It's true that photos help attract users to your post, but not sure if that will necessarily get you to digg front page

You need to put out good content and use social media sites also