I have a website and looking to migrate to use Google Apps for my email. But the thing is that I'm currently using Earthlink as my mail provider for my domain name. This also goes for using Earthlink as my domain registrar too. So I basically have everything there. I just want to only migrate my mail service to google apps safely without disruption. I know I have to change my MX records in the DNS settings. I'm not sure but how do I make earthlink as a failback MX server if the Google Apps doesnt link up right away? I dont want to risk losing any mail.What I dont understand is why is there so many MX records? And what are the numbers in front of it mean? Does that mean priority on which one to goto if the other ones dont work?Below I have my dns settings: 
Best and Safest Approach to Migrate Old Mail Service to Google Apps Gmail?
dns;domain registrar;mx