Threats are always present: there will always be script kiddies scanning the whole Internet to find vulnerable machines. A firewall is always a good idea to control incoming/outgoing connections.
As for updating, get swaret. It checks a list of mirrors for new packages or package updates. It's pretty neat.
I wouldn't worry that much if I were you. My slack router gets "attacked" often but it's mostly portscans or people trying to find anonymous ftps and such. With a properly configured firewall and updated system, don't have any worries