Two questions - colonization and reform criteria vs. AOR units

Hi.
I would like to thank the authors of this mod first for their efforts.
Then, I have two questions:
1) Colonization (KH)
-I do get the icon at the beginning of turn telling about colonists availability. However, it does not seem to do anything, is there anywhere description of what it does and how it affects the game and what I can do with the icon present that I cannot do with it absent, perhaps ideally with screenshots? I have been trying on clicking on various buttons while having city selected, but I can't observe any effect, not in buildings availability, and not in culture percentage in settlement details screen. I tried to google too, but most of links didn't worked (maybe because trying from smartphone).
2) Reforms of the subdued nations
-Say I am KH conquering Getai. Is there any advantage in vassalizing them, over just finishing them off? I have vassalized epirus (one city), which does not really do anything but build more armies (currently almost four full ones), but I wonder if there is any chance if leaving Getai as one province minor to get their armor upgrades for my Getai AOR units (swordsmen, nobles)?

One other point, I think I read somewhere Tylis is work in progress, so me not being able to recruit any military unit there as KH is I suppose expected?