How do you change avatars? I am a human, but don't like the "hunk" avatar you're given. Also, when you change avatars, does the change appear in all screens? TIA.

Click the "Record" icon on the left of the game screen. Then "Customize". Then "Appearance". You can change portraits by using the left and right triangles.

Though there is better portraits out there, then just those that are in the game, alot of modified and cool ones, they all can be found in the the sticky topic about mods etc, the portrait sites include also a guide on how to make custom portraits work.