Thucy, wow, lemme try, since "I don't know" is a permitted option. ;-)
1) Could God kill himself?
I don't know, but he came down and was born as the man, Jesus, who died for the sins of the world.
2) Could God limit his own power intentionally? In the same way that I might contractually bind my future self to do something?
I think he can do anything that doesn't contradict his own nature. And as Jesus, he put off the blinding glory of the godhead and walked among us in a way that we could see, touch, listen to--and kill.
3) Is this universe really the best possible one that could have been devised? Equal with all other possibilities, or what?
Growing up, I always thought I could do better, but the older I get, the more I realize that I have to trust God that yes, he really does know what he's doing, and he's doing it out of love.
4) Could God have been created by an even more powerful being? An equally powerful being? Along the same lines, could God clone himself and create another omnipotent being? If not, how powerful a being could God create?
God is one being, but he appears in three persons. And White Boy, *that's* a mystery!
5) Could God not lie to humans? I know that the teaching is that he is all good and never would do such a thing, but does anyone ever acknowledge the possibility? Personally, if I were an extremely powerful but not quite omnipotent being, I would find it pretty tempting to tell my pathetic cowering creations that I was omnipotent and all-good. Why not, right? Relatedly, what is your opinion of the Satanist belief that it is actually God who is evil and Satan who is good (Promethean figure, usually)? Nonsense?
Hmmm, kind of a three-part question, really--Were you hurrying up to get the last ones in? lol But... We see in the Bible that Jesus speaks in parables so that those who are seeking knowledge will understand. Is that lying? We also see that the demons, and Satan himself, believe in God--"and tremble." And we have the Tree of the Knowledge of Good and Evil in the Garden of Eden, and we all know what happened when Adam and Eve tasted *that* fruit. Conclusion: Too much knowledge isn't always good, but I don't know why, unless it can lead to pride, which was Satan's sin after all. Those are all good questions with no easy answers though, and I'm just sharing my own limited take on the answers.