Hey, Myen'Tal. Good to hear from you.
I think I will split Faris' story into multiple parts, just so I can spend the amount of time I want on certain scenes without rushing the pacing and making his development feel unrealistic.
The system that the agri-world is in has known peace for at least a couple centuries, so I wasn't thinking an Inquisitor would be "in the area" until the beginning of the story, but I guess that instead means the planetary governor is free to do the conscripting.
Doing some research, it looks like tomb-worlds are commonly just barren or desert worlds, but you are probably right in that so much time has passed that the eldar might have been able to terraform it, at least before the Fall. Still not sure which of the two I would go with. Even if the necron tomb-world doesn't work, I still have the eldar I can turn to.
As for the Space Marine chat, really the only part I think won't work is Faris asks him if he is afraid to die, and the Space Marine explains he is, but not the same say normal humans are. That instead he fears that, through death, he would fail his Emperor.
Again, thanks for your feedback. Any bit helps. ^^