I gotta ask, since you're hacking the snot out of what the game can do

What limits are there to the DMT mods and such in ability to change gameplay?
I have been in a few threads lamenting all the systems gone from the game, but I have no idea of what could be done to bring back with advanced modding, for example zombie corpse looting like in A16, weapon/engine assembly, smell, 1-600 Quality and Learn by doing.
LBD I think mostly can be done with XML modding, the rest I believe would need more advanced modding?