Ok here are some of my thoughts:
Gedo Mazo is the body of the 10 tails. The 100,000 zetsus are grown with the 1st's power, right, so if Madara implants on some of them all the sharingan he has, let's say 1 sharingan each, he probably has a Izanagi fast response squad (not for sure though, we still need to find out if one of those Zetsu's with an implanted sharingan has both the Uchiha and Senju powers, or only one of them/a small part of each and cannot use Izanagi).
About Madara's left side I will explain to you why it seems black. In the following picture I have took 2 panels from chapter 510 and circled the shadow on his forehead that implies that his left side is on the other side of the source of light thus it is shadowed. Madara's nose seems to also block out the light and there is still some mask that further reduces the quantity of light that falls on the left side of Madara's face. If you look at his left eye you can clearly see his sclera is also shaded, unlike his right eye. On the small support drawing I made the Madara is actually madara's head looked at from directly above him. If anyone doesn't understand the drawing let me know and I'll try to explain it in more detail. I hope this clears it up why half of his face is dark on those panels.
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My prediction for the next manga:
At an early point in 513 Kabuto will find out the island isn't there. Around pages 12-14 Gaara and anyone else who decided to go with him would have reached the island and will have a small chat with Naruto and the others and then suddenly at the last two pages a kunai/deidara bomb flies toward them and Kabuto is shown on the clay bird above them smirking. Maybe he'll even say "Ah, thought you could run away?"/"Gotcha".
By the way, I think it isn't necessary for him to carry 5 coffins everywhere with him, he can probably just summon the coffins and the dead Akatsuki members will already be in them ready to fight. This way it is more practical
