16 for aldor and 10 and 13 for te'hareth?
Aldor
16: Do they have a favorite creature in Faerûn?
He may be the personification of murder, but he really is an animal guy, so asking him to pick favorites is criminal. (That being said, he is quite fond of flumphs, and was a little disappointed when the mating ritual book turned out to be a dud)
Te'hareth
10: Are they proficient in playing any instruments?
They can shred on a guitar lute. (May or may not be starting the first githyanki metal band)
13: What are their thoughts on killing? Is it a necessary evil or do they enjoy it?
They're practical about it, as most githyanki are raised to be. They wouldn't kill someone simply because it was the simplest solution to a problem -- they'd at least try to find another way around, but if the person deserves it, who's to say they can't enjoy the vindication a little?