How many white dwarf stars are there in the Milky Way Galaxy? How old are the white dwarf stars in our galaxy?

No one knows.

It is nearly impossible for astronomers to see all the stars in the Milky Way Galaxy simply because we are a part of it.

This picture is a best guess of what the Milky Way might look like. Note that the location of is. Now remember that our galaxy is fairly flat. That means if you want to look at stars directly through the center of the galaxy, you must deal with the high density and brightness of our galaxy's center. None-the-less, astronomers at the Keck Observatory in Hawaii are attempting to do just that.

I like to tell students that if we have been very lucky, where astronomy is concerned, we might know about 1% of the universe. Why? Astronomers guess there are between 200 and 400 billion stars in the average galaxy. Now you must multiply that by the approximately 300 billion galaxies astronomers think exist. See the problem?