With a stronger ERE eastern christianity could remain united.
Also does Kieven Rus still go through the appanage period as in OTL?
Yes it could! Eastern Orthodox Christianity is very strong in the Byzantine Empire and Eastern Europe.
Pretty much, yes. Kievan Rus was too far North of the trade routes to be influenced by the Romans in any way.
Well it would have been col to see a modern Viking nation, as well as government and structure evolve. A great leader could have arisen, installed something like Spartan type govn't and with rigid structure and said it came to him/her(Viking Warrior QUEEN) as a "flash of insight" just like when Odin discovered the Runes...
I can't really see a war government last too long in Europe once modernization starts to occur. As Roman influence spans northward, the Norse government would break down from anger.
Perhaps if the Romans had indeed fallen when they did OTL, the Vikings would have had a better chance of surviving. But that's a totally different timeline