This is a very important part of a long run. The better you focus on helping your body recover the better you will feel and the sooner you will be back to your normal self.
As soon as you stop running you have a 15 minute window when reabsorption is at its best. Think liquids: fruit juice/carbohydrate drinks.
1 quart for every 30 minutes of exercise (this can be done over a long period of time)
A cold shower or cold water on the legs constricts blood vessels & muscle tissue preventing blood from pooling in the legs.
Recovery continues for 2-3 days after a long run.