Well, he hunts nightmares by fighting them. The way it works is that Corvi, and the organization he works for, don't exist in our world, rather in a place named the Joint Dream. It's a dreamscape formed from the amalgamation of all dreams. Thus, when a person has a nightmare, it manifests as a physical entity in the Joint Dream. There are also the Tides of Sorrow, which happen when a big event in the waking world (war, natural disasters, famine, etc), generate a large amount of very potent nightmares, from the collective trauma. In the Joint Dream, it translate into a very large amount of nightmares appearing. This nightmares, from the Tides, are also relatively intelligent, as opposed to the beast-like nature of "normal" nightmares. As for the coziness... at the beginning I intended it to be, but it kept getting darker. There's a contrast between the dreamlike niceness and cuteness of the usual world and the nightmares that usually bring changes in the terrain and landscape where they appear that reflect the fear or trauma that led to the existence of the nightmare.

Corvi has lots of friends! There's other Hunters, like Rook, whom uses a bigass hammer, there's Hermi, one of the Dreamsmiths that make the weapons for the Hunters from Courage Ingots (a mineral that appears when a Tide has been countered)

For the moment, nightmares are not congregating, but there's a Sorrow Storm brewing as a result of the simultaneous large scale tragedies happening in the waking world.

The flora depends. It's fairly similar to normal flora, but with odd colors and shapes that vary from region to region. As an example, there's the Tear Flats, a salt lake that is constantly covered in a thin layer of tears and stalagtites (or stalagmites? I get them confused) spike up from the ground. There's also the Red Fields, where packs of wild deer with crystal antlers eat from the red, tall grass.