yes a copper penny can corrode but it takes a long time for it to do so
YES! It does so very quickly.
When copper corrodes it turns green.
No, however, if copper pipe is going to be chased into the wall and plastered over, you need to use the highest graded copper. (class 2 or 3)
Iron generally corrodes faster because the oxide layer (rust) does not seal the metal's surface from oxygen like the corrosion on copper does.