Mariner 10 and MESSENGER.
Depends on the comet.
Personally no, and no other human has either.
Nobody has yet gone to the planet Mercury as yet, and I do not think that they will send anyone there. As it is hot.
The Sun doesn't revolve around Mercury, Mercury revolves around the Sun. For Mercury to revolve around the Sun, it takes 88 Earth days.
Mercury is a planet. By definition, it revolves around the sun.
Three are used for calculating the position - the fourth is for error correction.
No one has ever orbited Mercury, actually no human has ever gone farther than the Moon.
No. Humans have only been on Earth and the Moon.
no mercury does not have rings
Mercury has no moons.
Saturn has nine satalites. They are Dione, Enceladus, Hyperion, Iapetus, Mimas, Phoebe, Rhea, Tethys, Titan.
Mercury does not have any rings.