Also get on the tor-relays@lists.torproject.org mail list.
But the sad truth is that there aren't that many hosting providers that allow Tor relays. Especially exit relays, because of abuse complaints.
Also, as you might expect, Tor relays can use lots of bandwidth. It's more common to get flat-rate bandwidth for 100 Mbps uplinks, and metered bandwidth for 1 Gbps uplinks. Digital Ocean, for example, just switched to metered bandwidth, and that has killed some relays.
However, all this could arguably change, if Tor became mainstream, as part of Firefox.
That has no relation to the cases above which were of people running Tor exit nodes from their home. If one wants to hide their Tor usage then that's something else and there are pluggable transports that are already built-in the Tor Browser to obfuscate Tor traffic to look like something else--no need for a VPN.
If you're worried that law enforcement will knock on your door because somebody used your exit node for illegal internet activity, a VPN service (that does not log traffic) will give you additional protection by exposing their IP address, not yours.
They sometimes are. Not always. And they walk out free, except for that Jewish guy who lived in Austria (I can’t remember his name but he was the only one to get in real trouble for running an exit node).
Why take that trouble when they can do it directly using Tor without running any exit at home? Also for instance Bogatov had an alibi when that happened.
The forum I run only bans IP addresses caught posting link-spam. Which, admittedly, asymptotically approached 100% of Tor exit nodes before I instituted more rapid ban-expiration. I added faster ban-expiration after hearing from some of my privacy-conscious users that Tor had become unusable for my forum.
If you use tor and only visit onion sites, the sites don't know who visited them.
If you use tor and visit the regular web sites (like, say, HN), the last computer that does the actual request to the website is an exit node, as far as that site is concerned, the exit node made the http request. If you run an exit node, your computer is going to be doing tons of requests to all kinds of websites, this may include sites that deal in illegal stuff like drugs, child prostitution, human trafficking, terrorism, etc.
edit: Forgot to say, you must explicit be running an exit node. Not every tor node is an exit node.
You can be arrested for things just by using Tor if they mix you up with someone else or something?