Give or take, the Milky Way Galaxy has about 200 billion Stars. It takes light over 100,000 years to go from one side to the other, and it is composed of several 'arms' (composed of stars and gas) of various sizes spreading out from a central core. Nobody quite knows what's at the core of our galaxy, but the best guess is a Blackhole that is considered massive even in astrologial terms causing all the matter in the galaxy to orbit endlessly around it much like the earth orbits endlessly around the sun.
The milky way galaxy is home to millions of star systems, nebulas, you name it, the galaxies got it, it is our home system. The Milky way is a Barred Spiral Galaxy, meaning that the middle of the Galaxy is a bar with the spiral of arms circling outwards.
The Age of the Galaxy is hard to determine, at the moment today the oldest star that has been discovered is around 13 billion years old, and at the moment it is a Red Giant, The age of the galaxy has yet to be determined. The creation of the galaxy is hard to be determined also, the best theory is the Big Bang, meaning a large explosion of particles created the universe, while this is still under research, its really the only plausible explanation, experiments of the galaxies creation are being tested and researched at the Large Hadron Collider.
Like every other galaxy out there, theories have came forth to suggest that there might be a supermassive black hole driving this whole galaxy, however, such theories cannot be conveyed do to the lack of vision to the center of the galaxy, the dark matter covering the center has made it hard for astronomers to research and confirm such theories, possibly in the near future there will be more information on the center of the galaxy.
A hypothesized theory is that another fellow galaxy, the Andromeda Galaxy (formerly known as the Andromeda Nebula) is on a collision course with the Milky way galaxy, while this might not happen in over a billion years, it is a theory that is still being researched, if this were to happen, the two largest galaxies in the Local Cluster (which contains our galaxies and many others) will collide to create an even bigger galaxy, at the moment, our galaxy is, at the moment cannabilizing Large and Small Magellenic Clouds, meaning that we are making these two clouds apart of our community of Star systems.