As far as the alien artifact, I see Lex as being interested in ALL possible uses: energy source, weapon, whatever. He's curious, and he's obsessive, and naturally -- after his unpleasant encounters with aliens -- he's going to learn all he can about them and their technology. If I were in his place, I'd do exactly the same thing.

The Dominic kidnapping is a gray area, yes -- but Lex knew that only that sort of gesture would get Lionel to back off, and he took care of it himself, so there was no danger of Dominic being tortured or murdered by out-of-control subordinates. Oliver sent two minions, at least one of whom was clearly a sadist, and he never bothered checking in to make sure nothing was going wrong. And, after the fact, as I said, he shows no remorse whatsoever, which is NOT the reaction of a moral man.