I did the complete nub tutorial and it was quick and worth doing, even for someone that has played since there were only 8 colors on the screens 

It gets cancelled. I don't know what happens to the production though.What happens if I change culture while building emblematic districts of the previous Civ? Do they get cancelled? Will the production already used count as surplus, or be wasted?
It's +5 science per mountain iirc, so the "+10 from synergies on districts" should be the two mountains. But I wonder why it shows you +1/+8 on the tile itself, and not +11/+8...I know the Zhous emblamentic quarter gets science from mountains, and those two are obviously mountains, why does it only show 1 when I place it?
Spoiler :
What happens if I change culture while building emblematic districts of the previous Civ? Do they get cancelled? Will the production already used count as surplus, or be wasted?
Don’t know if it’s been asked before, but how does annexing work with the expansionist trait? I was playing as the teutons in the medieval, and was unable to use an army to ‘annex’ an administration centre with my army.. Are there steps you have to take to do this? I tried doing this in wartime (after being declared war on) and in peace
I know the Zhous emblamentic quarter gets science from mountains, and those two are obviously mountains, why does it only show 1 when I place it?
No, it doesn't flip. The Maya get a grievance against you ("oppressing my people"), which can easily lead to a war. There are also some events that can appear when you are in the sphere of influence of others, the osmosis ones, but also some narrative ones.Is there any effect if one of your regions/cities get 100% influence from another culture? When I check the influence it says that one of my regions with a city would go to the Maya in 8 turns, but I don't think it means the city would flip to them, right?
No, it doesn't flip. The Maya get a grievance against you ("oppressing my people"), which can easily lead to a war. There are also some events that can appear when you are in the sphere of influence of others, the osmosis ones, but also some narrative ones.
My experience with the expansionist ability is not very positive. You are interrupted very easy, and the AI usually does that. So my success rate was always very low. On the other hand, I think it isn't that useful. You can freely enter foreign territory as expansionist, and I think one of the strengths of the early expansionists is that you can just ransack enemy outposts without declaring war.