Acolyte of the Inferno's last ability will trigger once for each creature that blocks it. Each of those creatures will be dealt 2 damage.

Acolyte of the Inferno's last ability triggers and resolves before combat damage is dealt. If that causes each creature blocking Acolyte of the Inferno to be destroyed, Acolyte of the Inferno will remain blocked and neither deal nor be dealt combat damage.

Renown won't trigger when a creature deals combat damage to a planeswalker or another creature. It also won't trigger when a creature deals noncombat damage to a player.

If a creature with renown deals combat damage to its controller because that damage was redirected, renown will trigger.

If a renown ability triggers, but the creature leaves the battlefield before that ability resolves, the creature doesn't become renowned. Any ability that triggers "whenever a creature becomes renowned" won't trigger.