Looking at your faction list and being pm-ed to discuss the list before it is finalized, I just want to sudgestfew things.
Neither Abodrites, Veleti, nor Pomeranians are Polish. The first two are Polabians and the latter are descendants of present-day Kashubes.
Also, I am not sure that Croatians were Christians this early. Carinthians might have been due to their vicinity to Franks, but Crotians should be double checked.
Lastly, you have left out a faction most important in cultivation and spread of Christianity in Slavdom (perhaps after Bulgaria) Nitrian Principality. Churches were built decades before the arrival of two missionary brothers and its chieftain elites held a more amiable position toward Christianity. At the start of the frame it would still be largely pagan.
Those are mi few bits before making the list final. I hope this helps in clearign few things up.