Slitherine

I cant wrap my mind around one thing:

Why do we sometimes have 500 man squads, but sometimes 3000 men squads?

As far as the game mechanics go, the classic pike and shot means that you have:
only 500 men are fighting and shooting for foot, 250 for cavalry. ~70% of this number can do ranged attacks.
Casualty % for shooting and melee cohesion tests are based off current troop number but this value never exceeds 900.

By the way this line about 900 men has been expelled from the game manual? If so, why?

When i play 3000 men games i play with the new rules:
~3000 men are fighting and shooting for foot(even if you have a peasant mob of 7000). Thats why in 3000 games we are seeing huge combat numbers (i ve seen up to 450 troops killed in one hit)
for cav, i have not yet noticed which number is the limit.
Casualty % is based off the current strength but the limit is unknown.

500 is standard battalion size.

Scaling happens to better match the historical army sizes of a particular battle or campaign. Scaling also happens in P&S if you didn't notice.

Damage are also scaled at the same rate.

It is purely cosmetic, to allow armies of realistic size to be used in campaign and scenarios without exceeding the 64 units per side limit.

The 900 men "limit" will be scaled accordingly.

The scaling has no effect on anything except the numbers of men reported - in both units strengths and casualties.