Turb0 has been doing a great job with translation but this one has been bugging me so I'll rant a little. "Julius" should not be"Julius". It should be "Yurius". "S" chapters are about "Shun. "K" chapters are for "Katia". "B" is about "Bart". So why is "Y" "Julius"? It should be "Yurius"! /endrant.
Getting back on topic, [Warning: only read if you are really curious, I will try to keep the spoiler to minimum but... it's a spoiler >.>]
Spoiler (mouse over to view)
As of today, in fact, Kumo-chan completed her Arachne evolution and no, it's not her "final form"-ish. But the shape is almost like Shiro, so yes, I will say 100% that Shiro is Kumo-chan.
About Maou,
Spoiler (mouse over to view)
There is a being that is called Origin Taratect. That is all I'll say to keep the spoiler to minimum.