1.) Not sure where you saw that, but short description is for overviews (event-list, upcoming, calendar etc.). Long description is for detail view. It's only displayed in detail view, if there is NOT a long description.
2.) No, we need the ISO format here, else we can't format the date correctly.
3.) Hmm i think there is a setting in the menu entry for that (IIRC) if not you can hide it per CSS.