[Waddles]

So I have very recently learned family members and here is what I have.

My Family:
father = chichi
mother = haha
sister (older) = ane
sister (younger) = imouto
brother (older) = ani
brother (younger) = otouto

Your Family:
father = otousan
mother = okaasan
sister (older) = oneesan
sister (younger) = imoutosan
brother (older) = oniisan
brother (younger) = otoutosan

So I shall get to my questions...
How accurate are these nouns?
In anime (hate to bring that up) they call their brother or sister "oneechan" or "oniichan", so how do san and chan differ?
If I were to ask someone if they were the sister of someone else would I use "oneesan" or "ane"?
If I were to ask someone if a certain person was their sister would I use "oneesan" or "ane"?