An ice compress can be anything from a plastic bag filled with ice chips to a much fancier (and more effective) poly sack filled with a gel substance that doesn't freeze at normal freezer...
Ice is the solid form of water. It melts when the temperature of its environment is higher than the freezing point of water.
Crushed ice would melt faster because it has more surface area, and it probably has a less density than regular uncrushed ice.
With big refrigeration units.
yes there is