They arent squealing, they are chirping. This is how they communicate with one another. But if you only have one, it could just be chirping for fun :)
Dont worry about, it is normal. :)
Hermit crabs communication is very mysterious. We know that they make a clicking and chirping noise, especially when they are agitated. They also wave antennae at each other when they first meet but this could be just "feeling" each other out more than communication. So they do have the means to communicate but we do not know if they actually do it.
A lot
No, Hermit Crabs are omnivores.
fish and bigger hermit crabs
Yes hermit crabs have antennas.
No hermit crabs are small and friendly
sea birds, fish, octopuses, crabs, and other hermit crabs
it deppends on how big the hermit crabs and the moon crabs are but if the hermit crab is bigger youv'e got your self a dead moon crab
yes
Hermit crabs use meiosis to reproduce
no i had hermit crabs and had salt it didn't hurt them
no