The world is said to be a global village filled with people from different countries. People have friends from different part of the world and it becomes imperative to know where they are from for effective communication. You don't have to search for user info to know his/her location - just install Flags module to get flag icon next to user's name to know his/her location.
Sitemap is a tool that inform search engines about the structure of your site. By placing a sitemap on your website, you enable Search Engine crawlers (like Google) to find out what pages are present and which have recently changed, and to crawl your site accordingly. You don't have to manually submit sitemap as it automatically (if settings is enabled in the admincp) Notify Popular Search Engines (Google, Bing) when sitemap changes.