1. The short answer is no. The long answer is it's not two desires they have, more like two parts of the same desire.
2. Don't know about that. Hadou floods the entirety of existence, no matter how small or big.
3. Ten Sephiroth is the Kabbalah. You should ask Matthew Schroeder abouy that. He's well versed in that kinda stuff.
4. That's... Unclear. I guess their holy relic would be a joystick, their desire "I want life to be a game" and their Briah would be like, Hadou and createsca video game world with your laws. Atziluth is this on a grander scale and this time all the characters you can create are added to your legion ^_^
3. What I mean is that I have hearded that Claudia in Interview with Wilheim die because she doesnt have a stock of soul to maintained herself. So if a Die Ewigkeit user doesnt killed to gain soul then will they suffer the same fate as Cladia ??