Immolation Shaman's first ability resolves before the ability that caused it to trigger.

Immolation Shaman's first ability doesn't trigger when an opponent activates an ability of a card in hand (such as cycling) or a card in a graveyard (such as that of Bone Dragon), even if that causes a card to be put onto the battlefield.

Activating Immolation Shaman's second ability after one creature has blocked it won't cause Immolation Shaman to become unblocked.

Multiple instances of menace on the same creature are redundant.

Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities are activated abilities and will have colons in their reminder text (such as equip does). An activated mana ability is one that produces mana as it resolves, not one that costs mana to activate.