Kievan Rus’
The Kievan Rus’ isn’t exactly the best place on earth with its treatment of its population. You wouldn’t want to live in this place that’s for sure. The nation is very sparsely populated, filled with nomads, and in the middle of its conversion to Orthodox Christianity. This country is extremely isolationist as well and normally doesn’t conduct diplomacy with any nation other than the Romans for the appointment of bishops. They are mostly focused on colonization in areas north and east. It is also slowly but surely veering towards a trend of its nobility being more and more independent to the point that it’s more decentralized as France.
I like your TL pretty much but not the part concerning Kievan Rus.
I can't see how a diverging point so par away managed to change the course of Russian history so drammatically. There are a lot of differences with OTL because in OTL:
1) The treatment of population was not as bad as you imagine. At least it was much better than in most parts of Europe. There was no serfdom and the magority( or at least large parts) of population were literate and had the terrible habit to wash themselfs. Say Anna Yaroslavovna who married a French king wrote that Paris was a dirty village comparing to Kiev or any other major Russian town. In fact the middle of 11th century is the golden age of Rus history.
2) The density of population is indeed not too high but the territory is not "filled with nomads". In fact nomads while raiding Rus were succesfully beaten in most cases and Russians expanded into steppes quite rapidly. Say borders of Prinsipality of Pereyaslavl ( which helds the most of Rus borders with nomads) moved from Sula river to Samara River( the one that is Dniepr tributary) in the course of 11th century. And the main way to distinguish Russian terriory from steppes in fact was that nomads were not present on Russian territory.
3) This country wasn't isolationist. In fact it was one of very few periods when Russian had a lot of foreign contacts. Say Russian ruling hose in this period was married to most of ruling dinasties in other Europe. Say the three daughters of Yaroslav the Wise married three different Kings. One became the Wife of Henry I of France( the alreadymentioned Anna Yaroslavovna), the other one married the Hungarian King Andrew I and the last one Harald Hardrada( which can be butterflied). One of Yaroslav's sons married the sister of Casimir I of Poland, the other three were married on German, Austrian and Bythantine princesses. And yaroslav himself was married on the daugter of Olaf Eriksson of Sweden. And the trend of marrying European princes and princesses was due all the time before mongols came. Doesn't look too isolationistic for me.
4)While Kievan Rus indeed colonised the north-east( area around Vladimir) the most efforts of the state were concentrated in the South- cleaning steppes from nomads and settling them.
5)The middle of 11th century is the most centralised period of Rus history. And the state was pretty centralised before the death of Mstislav The Great (1132). And even after that you can't say that nobility took the power. The state dispersed but all the power was held in the hads of descendants of Vladimir Monomakh.
Of course some of the facts can change in your TL( say marriage with Harald Hardrada). But I don't see who the emergance of Vinland colony could change Russian history THAT much.