I think you're looking in the wrong direction. What you should be asking yourself is how did this npc get to this point in thier life?
Why did they join WoB?
What are the circumstances surrounding the incident that earned them MD status? You can't just volunteer, you have to be horribly managled in the line of duty and achieve this mangling in a noteworthy way that displays your devotion to the cause.
How has the NPC handled the psychological trauma associated with the wounds and then the cybernetics?
Is the NPC a die-hard true beleiver or meerly a loyal subject caught up in osmething bigger than they are?
Does the alteration of their bodies, alter their morals as well. Are methods that were reprehensible before now ok because you're doing them to simple frails rather than other MD?
Answers those and the rest will flow easily. Ultiamtely you'll find that the game mechancis of the cybernetics is a trivial detail and you'll find yourself just arbitrarily picking ones that fit the plot and the MD's previous military specialty.
-Jackmc