I think the ice in the drink is a remnant of the Kaiser spending time in the States. But other than that, using ice in drinks is rather uncommon in Germany (outside of cocktail bars and American fast-food franchises.)Someone else correct me if I'm wrong, but filling glasses with ice seems to be an American quirk? From my experience in OTL Germany it's rare outside of US franchised chains.
It's usually a handful of ice cubes added later in 'normal' gastronomy. Similar in private households that bother with it (the few that do) and usually more limited to the summer months.
Though a royal household might be different.