Re bleeding: I had a surgery professor who loved to intone "Significant bleeding is that which you can hear." In administering first aid, you don't need to stop all bleeding; you want to concentrate on stopping pulsatile bleeding that is emptying out your patient. Tourniquets, pressure points, and compression are the way to do that. You don't have to stop it, just reduce it to survivable levels. If you have a pulsing bleeder, those powders and such are going to be carried away. Pressure, control it, reduce it to something survivable. Get them to the OR with a pulse.