Try using a noclip cheat, that helps a ton to get you to places you couldn't reach if your collisions were activated. You should go in the command console (whenever you press ` it should show up), type in "sv_cheats 1" and "god" so you don't accidentally die making poses, and if the controls are default, pressing "v" should let you noclip.
When posing, press and hold the "use" key to rotate stuff (by default that should be your E key) while your physgun is active on a part.
Face posing is very simple compared to posing their body, legs, head, arms, etc. All you have to do is hold Q, go to the right, find the "Face-Pose" tool under "Posing", click it, shoot it on Fawful, then press C or Q to adjust the slider to change his facial expression.
Bodygroups are simple to. You can either download the "Easy Bodygroup Tool" off the workshop or hold C and right click Fawful and change his skin.