If Scute Swarm leaves the battlefield before its triggered ability resolves, the token will still enter the battlefield as a copy of Scute Swarm, using Scute Swarm's copiable values from when it was last on the battlefield.

The token copy will have Scute Swarm's ability. It will also be able to create copies of itself.

The token copy won't copy counters or damage marked on Scute Swarm, nor will it copy other effects that have changed Scute Swarm's power, toughness, types, color, and so on. Normally, this means the token will simply be a Scute Swarm, but if any copy effects have affected the original Scute Swarm, the token will take those into account.

A landfall ability triggers whenever a land you control enters for any reason. It triggers whenever you play a land, as well as whenever a spell or ability puts a land onto the battlefield under your control.

Whenever a land you control enters, each landfall ability of the permanents you control will trigger. You can put them   on the stack in any order. The last ability you put on the stack will be the first one to resolve (As a result, you can have those abilities resolve in the order of your choosing.).

A landfall ability doesn't trigger if a permanent already on the battlefield becomes a land.