Do all Nightmare know about Light Eaters?

The answer is: no

Most of the Nightmare population don't even know about Light Eaters, they know that they are curse but don't even know that curse has a physical form

The few Nightmares who do know about Light Eaters don't talk about it openly, that form is seen as weak and frail, and Nightmares don't like showing weakness.

This has actually help keep the true identity of the curse secret, everyone believe nightmare syndrome is like a sickness or disease that one can contract, they are unaware of Light Eater who are more like parasites.

Can Light Eater willingly remove themselves from their frames?

The answer is: no

It is extremely difficult to successfully remove a light Eater from their frame, the light Eater instinctively resists removal, being in their frame is natural to them and removing them feels unnatural to them, so a light Eater never want to be removed from their frame.

Because it is so difficult to remove a light Eater from it's frame and keep it in tact, a cure for nightmare syndrome has not been found, every time scientists or researchers try to extract the nightmare syndrome from a Dreamer or Nightmare it is black goo, that because they unknowingly killed the light Eater.

If the light Eater is killed the Nightmare frame will start breaking down without the light Eater to keep it functioning.

For a Dreamer if the Light Eater is removed, the light Eater going to cause as much damage to the heart reflection and heart as possible, if the light Eater going down there taking their host with them...

Is it possible for a male and female Light Eater to swamp frames?

The answer: yes but it's deadly.

It is possible for male and female to swap frames however this is unnatural for them.

A male light Eater is designed for a male Nightmare frame as a female is designed for a female Nightmare frame, if the two swapped it would be unnatural to them.

Light Eater are much like computer programs and this swapping would be like a error code to them.

The chemistry between male and female so vastly different with mental, physiologically and hormonally that if the two swapped frames eventually the light Eater would start having major errors that would cause them to go insane and eventually resulting in a system shutdown and die in that frame.

In the instant a male and female light eater swap frames, this is the only time you see a Light Eater want to be willingly removed from that frame so they can return to their proper frame

That all for this one