About 3 and a half kilograms
Goldfish excrete, yes.
Yes
Through their anus, same as you.
48kg per hour
about 1/2 a gram
Tetras (unlike goldfish), do not excrete a lot, so in essence they would be "clean" fish.
Under normal circumstances, it is best not to mix goldfish with other fish. They excrete higher amounts of ammonia, and it is harsh on the other fish in the tank.
the teddy gram would become mush and spread out in the water so a fish would win
There will be a problem either with the water or the diet. My advice is to do a few large water changes taking all the proper precautions and equalising all parameters. Then I would improve the fishes diet by adding a feed of earthworms at least once a week.
Yes they do. Many organisms including mammals, fish, fungi and microorganisms do excrete urea.
there are 4 or5 flavors of goldfish
The Language of Goldfish has 179 pages.