Tactics for the Swamp (Fortress).

That's correct. And the damage doesn't go below 1.

Yes, it doesn't go below 1 if there's only 1 creature in the attacking stack.

However, if there are 10 creatures in the stack, the damage of one of those 10 will definitely be less than 1, because the total damage, for example, of 10 Pikemen against 1 Gold Dragon will be approximately 5 damage.