They are probably spawning. The ones doing the chasing will be males the ones being chased will be the females. If you look closely at the fishes gill plates you will notice white dots/spots on them. There could also be the same kind of spots on the fishes pectoral fins. They are not disease they are the markings males of the species (Carassius sp.) develop when they are in breeding condition.
Yes, they do quite well together, I have both Comets and Shubunkin in a pond and they are very happy.
Two: There's commons and comets (Comets have longer fins). These are generally excluded from the "fancy" category. If you see a sign in your pet store labelling a non-fancy goldfish as "shubunkin", that's just the coloration. It's either a common goldfish, or a comet-tailed one.
The revole around the sun
Shubunkin is just a fancy name given to a specifically coloured Goldfish. Breeding one with a Golden coloured goldfish will result in about 33% that look like a Shubunkin and 33% that look like a Golden coloured goldfish and 33% that look like a mixture of the two. The above results would only be accurate if the breeder fish are properly line bred and their lineage is guaranteed. Otherwise you could get anything from coloured goldfish to uncoloured goldfish and a mixture of any kind of goldfish including Comets, Fantails and Veiltails.
Comets orbit the Sun.
ice
No. Mercury is the closest thing to the Sun, and comets are normally around the outer areas of the solar system.
yes, comets travel around the solar system :l
Comets have been around for the past four and a half billion years.
Bill Haley and The Comets
yes
Yes.