Dark Craft points: How do they work?

[Fyermind]

For reference Dark Craft Experience and Gold are located in the book of vile darkness on page 27.

My question comes from where it says only a single application may be applied at a time.
Does this mean that if I kill a commoner on an alter etc. etc. etc. for 100 darkcraft GP and kill another one for 60 darkcraft XP then a third for another 100 gp I can't use 200 darkcraft GP to make my next item?

Also, it never says much about who can be sacrificed, can I sacrifice a summoned celestial monkey? (assuming that I, the vile artificer I am can find a way to cast spells with the [good] descriptor)

[Jeraa]

You definitely can't combine the 2 Dark Craft gp rewards. You would be limited to only 100gp in that case. However, I don't know if you are only limited to using either Dark Craft XP or Dark Craft gp, or if you can use 1 application each of XP and gp. (I believe you can have a XP reward, and also apply a gp reward, but still only 1 of each.)

Summoned creatures don't actually exist, as they don't die when killed. I would say you can't sacrifice a summoned creature. (A called creature, on the other hand, does die when killed and so can be sacrificed.)