Google created Webmaster Tool as a way to connect your site to their server.
It is the fastest way to tell Google that your site is ready for ranking, and what has your site feed. Google uses this tool to notify you (through email) about the crawling errors, or SEO errors in your site.
Squirrly comes with the main tracking tools you need for your website.
Google Analytics is the main one. Squirrly will add all the new features from GA in order to use it at its full potential.
Facebook ID is used for both Open Graph and Facebook Insights. If you don’t know your ID, you can enter your Facebook profile URL, and Squirrly will grab the ID from it.