Yeah, specifications would be really nice.

Are you sure? Quail eggs translate to 꿩알. Im pretty sure 알 is used for eggs.

생선 is what you use to refer to a fish that is caught with the intention to be eaten, and 물고기 is any kind of fish, or like a pet fish

Yes. 생선 is when you are talking about the fish as food. 물고기 is when you are talking about it as a living creature (which seems counter-intuative, since 물고기 means water meat). Similar to beef/cow or pork/pig.

Yes! 생선 is cooked or dead fish, 물고기 is for living fish.

고기 means meat, so I think it should be 생선고기

생선is the food, while 물고기is the living version.

Either one is always fine, they are synonyms. 계란 is Sino Korean and 달걀 is Native Korean.