how big are the unit sizes

[Furious Mental]

I don't think unit sizes will go up in multiplications of two. I think they will increase by the standard unit size, i.e. the biggest units like spearmen will be 60, 120, 180 and 240. I say this because there are screenshots of 60 man units of peasants, and of 180 man units of peasants. So units will probably be
16-32-48-64
24-48-72-96
32-64-96-128
48-96-144-192
50-100-150-200
60-120-180-240

All taken this means that while the largest possible size of an army will remain the same, on average one will probably be fighting larger battles since the size of most infantry units on the largest setting will be 192 men, while cavalry will be 128.