Poop is wast that comes from your stomach
No
you can see fish poop it is just hard to see you have to really concentrate
from the rear
Yes fish poop.
Fish that have a stomach, generally secrete stomach acid (HCl). However, not all fish have a stomach. For example carp have no stomach and thus no stomach acid secretion.
You obviously did not do your homework when it comes to the fish you have and their needs. Sucker fish do not eat poop or rubbish. (No fish does that) They are tropical fish and they are algae eaters.
Yes, plecos are known to eat fish waste, including poop, as part of their diet.
their hindquarters
yes
out of their buttholes.
no