Wade-
On your first question, I have never seen a listing showing
a hundred coins but you bid on only a few. I would imagine it would be
OK as long as all the coins were the same and you wanted to buy a couple.
It would not be much different from someone showing a photo
of a single coin and saying multiples are available.
I may be wrong on this but
ebay doesn't really specify this in there guidelines.
Maybe someone else might have an idea.
Your second question.
ebay states-
"Include a clear picture of the actual coin being sold-
don't use stock photos" Some larger retailers do use stock photos but they have to
have permission from the rights owner to use it.
It can be confusing at times what is allowed and what isn't.