After the line that load 'MetadataPlayerA', the meta variables uses the metadata.txt files in order, so meta is the trainertypes internal number, meta is the walk name graphics, the meta is the player on bicycle graphics and so on. Simply change it to load the graphics created by your system.
Yes we will need more. :p
However, me and Mika are the only current content developers because the game engine isn't complete yet so even if we got more content scripters/developers they had nothing to do at this point
Again, I don't know without knowing exactly how your system works (and to be honest, I'm not interested in finding out). I would guess that the metadata Players would only be used to set the player's trainer type, which means you would need one Player per trainer type.
Is there any reason why you're asking me about a system I don't know, rather than trying it out for yourself?
I don't know what your character creation system actually does, so I can't possibly say anything definite.
Assuming it works the way I imagine it might, then no. The compiler only reads in the metadata.txt file (as well as the other PBS files, obviously), but your system would ignore all the Player information in favour of a different way of deciding which graphics/trainer type the player uses.