Yeah, Foster makes a point of making sure it's mentioned that Vader is alive at the end of the story. I assume he left it so Vader could make an appearance in the third story\film.

Luke and Leia use the crystal to heal their wounds at the end of the story and then give it to Halla before they leave. I forgot what happened to the splinter. Seems like they lose it early in the story after the're first captured. I think Grammel keeps it.

I have the book sitting on the desk in front of me now, ready for a summer read. Probably start in a month or so. Been over a year since I read it.