If you were browsing with Windows on an out-of-date Firefox with JS enabled, you were vulnerable to the exploit.

If you visited certain Tor hidden services (*.onion sites) during that period, [bad stuff] would have happened. I haven't seen reports of the exploit being done outside Tor, but probably theoretically it could have been elsewhere.

I can't remember or be bothered to check if [bad stuff] was more severe than revealing your IP address (which is the main point of Tor; to hide your IP and other identifying details from the server you're visiting, hence why this is a big deal, but potentially not if you weren't doing anything where knowing your identity matters).

If you don't use the Tor browser bundle, there's a good chance your specific browser configuration already makes you pretty identifiable - especially if you have Flash/Java/Silverlight plugins installed.

Some Tor nodes will block BitTorrent and similar because the way it works cause lots of traffic, but for general everyday browsing it's fine, and the the only reason not to it is because it's slower.

If everyone used Tor it would make identification through traffic analysis more difficult to perform (needles/haystacks), which of course helps with the goal of hiding identity.

Being an exit node is a good thing though - again, it helps to spread the load. makes it faster, makes traffic analysis harder and so on - and if you have the bandwidth to spare it's easy to setup:

https://www.torproject.org/docs/tor-doc-relay.html.en