Thanks for the kind words!
I don't believe it's possible to vary arrow quantities for a single unit. Making a note of how many arrows each unit has is a possibility, of course. But I'm not sure it's a necessary feature. There is one exception I'm aware of: the Company of the Black Arrow has double the amount of arrows that the Black Arrows unit has, and that is indicated in the unit description.
Population has been tweaked quite a bit over the mod's development. Overall, we wanted growth to be low, and there are only so many 'steps' to population growth. I think it unlikely population will be tweaked further. But thank you again for the feedback!