How To Get Google Sitelinks
The last question is: what are the benefits of having Google sitelinks? I believe there are two, one tangible and one intangible. The tangible benefit is an increase in traffic for your website, because the sitelinks will give you more exposure in the search results, increasing the CTR you will get on search queries.
The intangible benefit is the credibility that you get from having sitelinks. Only established and authority sites have sitelinks, so when users come across them after searching for the name of your website or blog they will get a reassurance from Google itself that your content or products must be good.