heyo so I've been trying to modify the rig to look more like this guy show on the main Malcolm page: link to page

initially tried just moving and scaling existing face/arm/shoulder controllers, however while some work alright others scale really strange and not uniform and even ones that work seem to break later in animation.

is there a better way of modifying the overall body/face look for Malcolm in the least destructive way?
or is it a case of unbinding the mesh scaling to size then copy skin weights?

You can use those purple controls (ctlDirect*) to reshape parts of the rig.
You can translate and scale other controls but yes you do run the risk of interfering with the rig's operation. There is no set way to do this but if you are our student we can meet with you in Model/Rig General Reviews.