How do the lotus eater pose a threat to odysseus and his men? what does the description of the incident with the lotus eaters add to the epic? why doesn’t odysseus elaborate further on his description of this incident? how does this encounter with the lotus eater contrast with odysseus approach to the cicones?

The lotus that they eat fills men with contentment. If they become contented just eating lotus, they would never keep their ambitions to go home, and thus never go home.
In Book IX of Homer's epic tale of the brave warrior Odysseus and his ten-year journey home to his wife and son, The Odyssey, the story's protagonist and his crew find themselves, having narrowly escaped Ismarus, and the city of Cicons, washed upon the shores of "the land of the Lotus-eater, who live on a food that comes from a kind of flower." That food, the "lotus," apparently has a strange, drug-like effect on those who consume it. Odysseus explains that the land's inhabitants are seemingly "drunk" from consuming the fruit of this plant and that, while apparently harmless, these peculiar people seemed to wander aimlessly. Indeed, when a detachment of Odysseus's crew is sent ahead to scout the situation, they are fed these same plants, and now are completely ambivalent about their journey home. As Odysseus describes the situation, "those who ate of it left off caring about home," and wanted nothing more than to stay in this strange land and continue to consume the lotus plant.
Not wanting to lose more of his men to this addictive plant, Odysseus orders the remaining members of the crew back on board the vessel, and he beats a hasty retreat. It is at this point, however, that the crew, with its next landing, encounters one of its most dangerous obstacles, the one-eyed giant called Cyclops, who will proceed to consume some of Odysseus's crew until the resourceful leader succeeds in blinding it and escaping once again.