Running an entry or exit node is kinda risky since your IP will be associated with a lot of illegal content. Running an intermediary node is much safer. All kinds of nodes are important for the network.

The amount of configuration you need to run a node isn't terribly difficult. There is plenty of documentation online and really it's just changing a few lines in the config file. The Tor daemon is pretty good about pointing out potentially undesirable configuration options if you watch the log file on startup.