Decreasing temperature will decrease the rate of reaction to such an extent that no ammonia is produced.

Increasing pressure and decreasing temperature have opposing effects on the equilibrium, canceling each other out.

Increasing pressure favors the formation of ammonia due to fewer gas molecules on the product side, and decreasing temperature favors the exothermic forward reaction, both actions increasing ammonia yield.

Increasing pressure has no effect on the equilibrium position because the system will adjust to negate the change in conditions.