Moraug, Fury of Akoum

Moraug's first ability counts how many times a creature has attacked, not how many times it has dealt damage. The first time a creature attacks in a turn, the +1/+0 bonus will apply to the combat damage it deals during that combat.

There won't be an additional main phase after the additional combat phase. For example, if the landfall ability resolves twice during your postcombat main phase, you'll get two consecutive additional combat phases after your main phase (untapping your creatures at the beginning of each), followed by your ending phase.

A creature that enters the battlefield attacking hasn't attacked that combat. Moraug's ability won't count that combat. Unless that creature has haste, it won't be able to attack in additional combats this turn.