If I buy VPS and create Tor exit node there what would happen if someone did bad thing using my exit node? (terrorism, hacking goverment sites etc) VPS provider will share information about me to FBI or another goverment organizations or just will send abuse and block my VPS because it's obviously that I'm just an operator of exit node, not terrorist?
It depends on your definition of dangerous. Since I assume you aren't going to save any logs even if you're subpoenaed you don't have anything to turn over. It's not dangerous, but it certainly might be a hassle. Exit nodes are typically run by non-profits or those entities that have the time and money to address any issues that come up. Individuals are typically better off running a guard or middle node. If you're willing to deal with the hassle, please go for the exit! They are by far the most needed.
If you're worried about running an exit relay, and legalities involved, the following may help put your mind at rest:
- The Tor blog has an entry on how to run an exit node with minimal harassment
- The EFF has a page on the legalities involved in Tor, including a specific section on exit relays
If you do run an exit relay (which is a great thing to do!), and you do get a take-down request from your ISP, then the Tor wiki has some templates that you can use to create a well-worded response. (This is linked to from the Tor FAQ.)