World War 2 reenacting is unique in that there are enough of both private and public battles for a person to be largely devoted to one category or the other, although most people go to both types on a regular basis. That applies even to heavier equipment such as artillery and tanks. Aircraft are few and far between, with their only involvement being staged strafing runs against ground targets. Fully automatic machine guns and sub-machine guns are quite common. The most common vehicles are jeeps, motorcycles, and similar, utility type vehicles such as 1940's pick-up trucks.
All weapons use blanks or other means that can safely simulate the weapon's use.
In public events, it is decided before hand the casualties that will be suffered at different points. Who takes those casualties is up to the reenactors. At private events, it's a different story. One way that is used, that I use to some extent myself, is to watch the flash from the opposing sides weapons. If the flash is perfectly round, the shot was probably aimed at me.