Cut the hen into 8 pieces and discard any excess fat. Rinse chicken bones and necks with cold water and place in a stockpot. Add the water and ginger and bring to a boil. Skim any foam that rises to the surface. Reduce the heat to a low simmer and cook for 3 hours; do not allow the liquid to boil to ensure a clear broth.
Remove and discard the hen and bones. Strain the broth through a fine mesh sieve or chinois lined with cheesecloth. Return the broth to a large soup pot and continue to simmer until reduced to a volume of 2 1/2 or 3 quarts. Season with salt, to taste, and keep hot while you assemble the remaining ingredients.
Prepare the rice vermicelli according to package directions. Once done, transfer to a colander and drain well. Rinse well under cold running water. Drain thoroughly before using. (The noodles may be prepared up to this point 2 hours ahead of serving.)
When ready to serve the soup, for each serving ladle 2 cups of the hot broth into a large soup bowl. Quickly dip the cooked noodles in the remaining hot broth to rewarm, then place a handful of noodles in each bowl. Divide the sliced chicken breast between the bowls, laying the slices over the top of the noodles. Serve the soup immediately, with the fresh cilantro, basil, mint, bean sprouts, lime wedges and jalapeno peppers in baskets on the table for each person to garnish their own soup, as desired. Add chili sauce or fish sauce, to taste, if desired.