So I was told that as long as I stand behind the pile of wood to kill the two Ganado in the village, that the second wave would spawn at the far end.

That worked. They spawned. Two other questions I have

1. What causes the cutscene to trigger after throwing the grenade down the ladder? Do all the ganado just spawn there or do they pile there to take turns climbing up the ladder?

2. Someone told me you could pick up the pendant before it drops into the pile of poo (read: without shooting the lid down) in the next area. Is that possible?