See Installation for available packages and building from source options.
See Configuration for configuration.
Gossip is a GUI desktop program, but it also outputs a lot of messages to the console as it runs. I recommend you keep the console open and pay some attention to errors or other odd behavior that may become apparent from the console messages.
Gossip has a lot of command line commands for tweaking things or extracting bits of information from its database.
See Gossip Commands
See Troubleshooting.