Overview Of Photoshop/Character Animator Relationships

1/ I have never set origins in the artwork file. You can drag them around in CH afterwards if you need to adjust them. I rarely have touched them, apart from attaching child independent layers to their parent.

2/ CH computes the mesh automatically by doing contour tracing of your artwork. No need for you to create a hidden mesh, unless you want a mesh shape different to the artwork. Or if you have two unconnected bits of artwork you want to connect with transparent "joiners"... But that is unusual.

3/ I do all triggers and swapsets in CH, not in the Photoshop artwork file. I don't know of any magic layer names you can use (but they might exist...). It gets hard because you potentially want to bind keyboard keys and MIDI notes to triggers. That is pretty hard via layer names! It might be possible, but I have never done it and never missed it.

4/ Not sure the key bindings available. I usually just try them in CH. If it accepts the key, it works! If not, try another key. I know letters and numbers work. Function keys do not. Not sure about punctuation. (And interesting! I did not know you could put the key binding names inside the Photoshop file layer names. I am not sure I like it to be honest. Sometimes you want to create one trigger that controls multiple layers, other times you want multiple triggers that are triggered by the same key stroke. I doubt you get this level of control from Photoshop layer names...). You cannot do everything in Photoshop layer names, so at some point I just use CH. Independence is useful, beyond that I just do by hand.

5/ I would definitely nest it. It is cleaner organizationally, plus it can avoid some problems. E.g. you can add behaviors to the "Head" layer and they will not accidentally bind to the body profiles. E.g. Head Turner you can add to the Head layer and it won't accidentally pick up the body profiles by mistake.