So, I created a new user with the adduser command, but forgot to add the audio group... Should I just edit /etc/group by hand? Also, there's no usermod, so if I want someone's "real name" or phone number (I know, I know, no one's gonna finger this box), also just edit /etc/passwd by hand?

Are there any other groups I need to add to besides audio to do basic, day-to-day things? No permissions messages coming up when someone plugs in a USB stick or tries to save a word processing file?