The normal words are ある and いる. But in colloquial, we say あるの、あるよ、あるのよ、あるね、いるの、いるよ、いるのよ、いるね、and so on. They are casual words and we use them between friend or family. I guess it is not こわくないお. If is こわくないよ, it means as same as こわくない+ よ(colloquial). Hope it helps you.

I don't know what is point actually, because we don't use こわくないお/こわいないを。 You know こわい. It means get scared. こわくない means "I'm not scared" Is that answer that you want to know? If it isn't, sorry..