The penis is a labial body. His erection is produced as a result of tissue filling with blood, like a sponge draws in water. That is, there are a lot of blood vessels, so the blood will flow in a pulsating fountain and the pressure will be very strong. To close the wound, you need to firmly press the amputation site with your fist) to stop the blood and quickly go to the surgery or call an ambulance.
The cells will die due to lack of oxygen.
Not for long. In a couple of seconds he will not be erogenous. The processes in it will be simple - blood will gush out of it (not for long) and then its tissues will slowly die from oxygen starvation.
P / S. Just in case, if anything, throw it straight into the ice and take it to the surgery. And don't forget the owner. They say they sew on ...