The Dolphin Fresco is from the ancient Minoans Culture/civilisation in crete
Because they wanted to adorn the palace.
It was said to bring the native people great fod from it's offspring. The way it showed culture was when the natives spoke about the dreans where they saw the mother whale dancing.
Yes, Winter the dolphin is real
Yes, a female dolphin cannot sexually reproduce and have a baby dolphin without the male dolphin.