Here is most of the new info from the French Stream, courtesy of Serenes Forest.
Raphael needs Heavy armor and Strength to recruit.
Fodlan is about 2/3 of Europe by size. You will discover the countries around it during the game. The 3 fodlan countries are united under Seiros to prevent invasion from the countries around.
The characters can refuse to have tea with you. There was a " 3 missing conversations" screen at the end, dont know what that means.
Using general amiibo gives items, using a Fire Emblem character will unlock their character music that can be used on free battles.
There is a "help class" option to recruit a student from another house for only a month.
There are beasts that take 6 squares. Difficult ennemies as beasts was a long time desire from the producers, just like the many fighters on screen.
Some notes: Petra makes very obvious mistakes with her grammar but tries to get better. The French localization seems nice. Dorothea said something mysterious during lunch (she feels like she liked that before, but doesn't quite remember) so maybe she has some secrets...
Finally, the producers tried a lot of new things and had to face many so they are a little stressed about the reception but hope we will like it. Also they consider each story line as a game so Three Houses is 3 games in one