How: After a previous universe came to an extremely swift close, an extremely dense “ball” (and I use that term loosely) of energy proceeded to create literally the largest and most spectacular cosmic fireworks display ever seen in our universe. This was called the Big Bang. As the universe expanded, the speed of expansion began to accumulate speed, oddly enough, to the rate it is currently at. By some unknown method, energy began to shift into mass (Higgs Boson possibly?) and clouds of particulate were formed which gave birth to stars which ensnared other cosmically created bodies into their gravitational fields.
Other Galaxies: I thouroughly believe that there are countless other galaxies with intelligent life within them. In fact I believe that there is other intelligent life within our own(we have a pretty big back yard).
Multiverses: Yes, I believe that our universe is one of many. How, exactly, are these connected to each other, I have not the slightest.
Hope that answers your questions.