What happens when True Kin capture a Craftworlder or Corsair?

Lets say in the instance of a successful raid or in the event that the True Kin encounter some of their cousins in the webway, the DE successfully defeat an Eldar or Eldar corsair force. Obviously the death of Craftworlders then become apart of their spiritstones. What would a Kabalite do with such a thing? Would they even know what that is? What about captured Eldar or Corsairs? I always felt that while torturing for eternity or slavery for the captured cousin would definately be on the table, the idea of giving up these guy's soul to Slaanesh while tempting(Probably the most torturous fate to bring to someone) they wouldn't actually get to experience it so it would be pointless AND I thought with the whole "no psykers allowed" rules in Commorragh, I almost could see this being one of them. Strengthening Slaanesh would probably be frowned upon. Is there clarification on this specific instance?

Next up, if said captured Eldar, Corsair or Craftworlder, was beaten near death what happens if they're put say, next to the pits of wracks or other tortured whatevers? Would they be able to asborb the whole pain/suffering for sustenance like True Kin? Forgive me if i'm wrong but I haven't really seen anything the states any biological differences between the two, just they all deal with staving off Slaanesh in different ways.

The books state that they are essentially the same species. So a Craftworld Eldar is different from a true Eldar because of his culture. Nothing else. And about the stones:

I.guess giving them to the Haemonculus to power some arcane weapons seems like the proper usage. The Incubbi have one of those if I'm not mistaken.

They wouldn't want to feed Slaanesh. The Dark Eldar despise slaanesh as much as any other eldar. They just have their own way of staving off "she who thirsts". They use regeneration instead of spirit stones. Essentially, as long as a single cell of their being remains alive to be regenerated, their souls aren't claimed, insofar as I understand it.

Biologically there is no difference between an Exodite, Corsair, Craftworld, Harlequin, or True Kin. They are just different cultures and in the case of True Kin they have allowed their Psionic abilities atrophy so as to better protect themselves from the beings in the warp while the other cultures have not taken this approach.

Like you said Craftworlders go to their spirit stones, as Betray said True Kin, if they can afford it, regenerate their bodies and their souls are some how bound to their cells. Exodites have spirit stones I would assume as well as they have infinity circuits on their worlds, and Corsairs are drawn from all groups save the Harlequins, so some are from the Exodite worlds, others are craftworlders, and some are True Kin. I haven't come across anywhere that specifically states what happens to their souls. Harlequins are supposedly protected by the Laughing God.

What do the True Kin do with their cousins when they take them in battle or a raid. Well truthfully I would say they do what ever they feel like. But very few of them would ever think about empowering Slaanesh. It is mentioned in the 5th edition fluff that the incubi take spirit stones and twist them making them into a weapon. Psykers would be handed over to the Haemonculus to create Crucibles of Malediction most likely. Maybe some Archons might even attempt to convert the occasional cousin by exposing them to the exhilarations of their own culture and get them to become pain junkies too. I really think it depends on who the Archon is and what their particular personality quirks would have them doing to prisoners of any race.

If taken alive they would need to suppress their Psionic abilities to make sure they don't break the taboo in the city and bring the wrath of Vect and the other Kabals down on them.