We haven't sent any spacecraft to Betelgeuse, it is much too far. However, the Hubble Space Telescope has studied Betelgeuse, so I guess that counts.
betelgeuse
No. Betelgeuse is a single star.
No, Betelgeuse is a red giant star.
No. Betelgeuse is in Orion.
Betelgeuse is brighter.
a doctorinmay
Voyager 2
Billions.
No spacecraft has ever landed on Mercury, but it was studied by Mariner 10 and MESSENGER.
Voyager 2 is the only space craft that has studied Neptune, other than The Hubble Space Telescope
No sadly not. It is the only planet not (when this answer was written) planed to be studied by spacecraft. Poor Uranus.
No, spacecraft till now has made it to mercury as it wasn't allowed and was dangerous to life.
betelgeuse
No. Betelgeuse does not affect us.
No. Betelgeuse is a single star.
No, Betelgeuse is a red star.
Betelgeuse is a supergiant star.