Re: Where are Hizashis eyes!
I think he still has his normal Byakugan and as the reason as why his eyes are still white, well then you can also ask yourself the question why don't they have black pupils when they're alive? Overall seen most characterss have black pupils and irises (this is going to be a bit complicated because some characters like Naruto and Sakura have pupils and irises in a different color) and the rest of their eyes is white. This is reverted by Edo tensei: the eyes become black and the pupils/irises white.
But then there are only two possibilities: or the Hyuuga eyes remain completely white (as the colors of the eyes and pupils/irises switch, but in this case the color is the same) or they would turn completely black. Hyuuga's have a doujutsu, but they're the only of the 3 doujutsu's that has even in a natural state special eyes. Uchiha and Rinnegan users have normal eyes, they can activate their doujutsu and then their eyes change. There isn't a clear picture of both Nagato's and Itachi's eyes after beying summoned, though their eyes are probably not activated, so their eyes will be mainly black.
That shibberish aside there is one good reason as why he would still have got his Byakugan: why the hell would he be summoned if he can't use it? Especially Nagato and Hizashi as their strenght solely comes from their eyes. Nagato is a skeleton, he can't do much without his eyes and Hizashi isn't that much better without his Byakugan =/ Itachi was a genius, so even without the Sharingan he's strong, but still he was so infamous for his Sharingan. Without their eyes they weren't really worth summoning and it has been said in the manga and you stated it yourself: kg are resurrected with the user.
There is one thing you are not entirely correct, it's not someone who is sealed that can't be brought back by Edo Tensei, it's his soul. If his soul is sealed he can't be brought back, however the physical state of his original body is completely irrelevant. Some people here are saying "his eyes got sealed" and because it says "sealed" they immediately draw the link between when a soul that is sealed can't be resurrected and thus the eyes can't be either. That's not a right conclusion. The seal on the Hyuuga's eyes wasn't meant for Edo Tensei, it was meant to keep people from transplanting or researching the Byakugan from the original body. However the Edo Tensei's don't have their original bodies anymore. Deidara was blown up, Itachi's eyes are in Sasuke's head now, Nagato's eyes are in (at least one) in Madara's head. Still they were all summoned. The state of the original body doesn't matter in Edo Tensei. Not to mention that Hizashi doesn't even have eyes anymore, he's been dead for a decade O_o, he only has got bones left.
I'm not saying it is, though using logical deduction he can use his eyes as those are not the eyes that got sealed. Hizashi's soul was resurrected with all his skills, even KG, but not his original body. It's a bit difficult to visualize, but the original bodies of the owners don't matter. Sealed or not, the only thing that is needed is a bit of DNA, so Kabuto just needs Hizashi's toenail to bring him back.