I literally spent weeks last year grepping the entire Mavericks base installation for hardcoded URLs, domain names and IP addresses and setting up entries in /etc/hosts and NAT rules to hardwire that stuff to 127.0.0.1. I also had to disable lots of LaunchServices/Agents to get the OS to shut up. Can put this up on Github if there is interest. It's only for Mavericks though, couldn't be bothered to upgrade to Yosemite as long as there are security updates for Mavericks.
Oh and another thing a lot of people don't know: The OS stores Wifi passwords in EFI boot variables. This is used for Internet Recovery. So if your device is stolen or just lent to someone else, consider your Wifi passwords compromised, regardless if the disk was encrypted.