In the "Warriors" series by Erin Hunter, the term "twoleg" refers to humans. Twolegs are the creatures that the cats in the series encounter and interact with, often causing trouble or posing threats to the Clans. In the specific instance you mentioned, the twoleg causing harm to the cats is likely a human engaging in activities that endanger the lives of the cats in the story.
it was a twoleg nest and it wasn't leafpool who got locked up it was graystripe and yes he does escape.
It was Leafpool, Jayfeather, and Squirrelflight who prepared the abandoned Twoleg nest as a sanctuary for the cats with greencough in "Warriors: Long Shadows." This was a clever solution to separate the sick cats from the healthy ones and prevent the spread of the illness.
There was never any reference to Firestar's Twoleg's name.
First of all, there are 2 Ivytail. The Ivytail of RiverClan was an elder in Twilight, where she died of Twoleg poisoning. The Ivytail from ShadowClan started her apprenticeship in The Sight and became a warrior in Outcast.
It never says, as they were born between books, but most likely they were born either in the Medicine cat's den, or, as Yellowfang's were, out on the territory. This is because Leafpool, as a medicine cat, had to hide the fact that she was kitting. She then must have given them to her sister so the clan didn't suspect anything.
No. That is a Twoleg name.
He was helping Squirrelflight, and some other cats of ThunderClan rescue the cats that the Twolegs had trapped, like Mistyfoot, Leafpool, and Gorsetail. He stayed behind to help open Brightheart's cage, and the Twolegs grabbed him.
He was hit by a twoleg monster. (Monsters means cars)
Graystripe met Millie at a Twoleg's place when he was captured by Twolegs.
Cody is a kittypet in the warriors book "Dawn". She was in a neighboring cage with Leafpool when they were trapped in a Twoleg nest. When they were later rescued, Cody stayed in Thunderclan for a while, but eventually went back to her Twolegs.
Warriors: Power of Three: Book 5: Long Shadows
She didn't die. They left the forest. She stayed behind at her Twoleg home, so it doesn't mention her again.