First, I have to say that I love everything in this DD and all the news we got since yesterday. I have a few questions, though:
1) You said there will always be 1 pop assimilated/converted at a time. Did you mean per city or per province? (or per faction, but I doubt it). Also, will it be "1 pop being converted and 1 being assimilated" OR "1 being converted or 1 being assimilated"?
2) Will active pop promotion disapear entirely? I don't care about assimilation and conversion being passive only with the player only influencing it indirectly, but promotion is the only instance in which I think the ruler should be able to take an active role with an instant effect, passing an edict to free hundred of slaves or grant citizenship to hundred of freemen at a time isn't so farfetched (it may however cause in increase in tyranny)