There are no comets on Neptune because Neptune is a planet and comets are, well, comets. They have nothing to do with each other.
No. Comets come from beyond the asteroid belt, mostly from a region called the Kuiper Belt, beyond the orbit of Neptune.
Most are thought to come from the kuiper belt, further out than the orbit of Neptune. Long term comets may also come from the Oort cloud, which is further out still.
yes
Beyond the orbit of Neptune
-- Despite where they come from, some comets have different mass qualities. While some are long-term comets, some are short-term. Short-term period comets originate in the Kuiper belt or it's "shattered disc", which is around the orbit of Neptune. Long-term period comets originate in Oort cloud, which is a cloud of icy bodies in space.
an Oort Cloud
Comets are relatively small chunks of rock and ice that orbit the sun, sometimes they come close but usually are far out beyond the orbit of Neptune. Stars are different, they are like our sun. Much bigger and hotter but much further away.
They come from the outer reaches of space.
Comets come from the Oort cloud and the Kupier Belt
Asteroids are minor planets, especially those of the Inner Solar System. However, between the orbital paths of Mars and Jupiter lie a region known as the asteroid belt. Many asteroids come from there, but most of them stay there. Short-period comets originate from the Kuiper Belt, just outside the orbit of Neptune, while long-period comets are thought to originate in the Oort cloud.
It is believed that there is a large cloud of comets, called the Oort Cloud, orbiting the Sun at a relatively large distance. Now and then, one of them is budged by gravitational forces; as a result, they come closer to the Sun - where we are.