Yes, at least I think so. Here's how I see it, people could say "Oh, he/she is just like that, he/she is just quiet". Sure, you could be quiet temporarily, but you could also just be "a quiet person" so that's what I think.
Quiet.
quiet, quaint, ...
A character trait is basically the personality of someone. For example my character trait can be generous.
Yes, any personality trait is a character trait.
No it isn't a character trait.
no. special is not a character trait. you can say that the character is special.
Yes, it is a character trait.
Yes, it may be a character trait.
Yes, hopeful is a character trait.
Impulsiveness is not a character trait. Being impulsive would be classified as a personality trait.
A character trait is ANYTHING about the character. You can't make a list of all of them.
Yes, anything that describes the character's personality or appearance is a character trait.