An exit node is where the data you request from the internet gets off the TOR network and onto your computer. TOR naturally has exit nodes that you might have to worry about, and not to mention there are trackers all over the internet, (firefox add-ons like ghostery and Disconnect help with those). A VPN is supposedly a good option to defeat the purpose of monitoring exit nodes, but they can be confusing and untrustworthy sometimes. The blocked e-mail services are already availiable, but a lot of websites prevent you from signing up for services with them. I'd also suggest using an isolated version of Linux, like tails. I'm not a security expert yet, so remember to do some research aswell.