The Site Links are from the Post Categories and Tags. Yes I have a Sitemap which is submitted through Google Webmaster Tools. Averaging around 1000 unique page views per day. Hope it Helps
What is the keyword your searched for? If you just search your domain name, your website will certainly get the first place on ranking.
We are not talking about search engine position we are talking about Google Site Links. Suggest you read the first post again!