Now to figure out which "please" is used when. "Per favore" or "Per piacere"?
As a native speaker I can't see any difference between the two. They both mean "Do me a favour", litterally speaking, and I can't think of any example where "per piacere" is used in more official situations.
Yep, they are perfectly interchangeable.
Yes, good question.. I have a feeling "per favore" is more common talk and "Per piacere" is more official such as warnings and cautions..