YES!!!!! The oils on your skin will get into the water, and the fish will "breath" it in and it's kind of toxic!
Very fast. I don't think their speed has ever been measured/calculated accurately though.
when water temp is same as where ther at now,
Koi is a type of fish. Just don't put koi in the pond and it will not be a koi pond.
Provided the pond has been built properly to a sensible and serviceable design with lgikukvkjblkj