If you can see the various beliefs that gods exist as something additional to the common human outlook, and then see atheism as the simple absence of that additional belief, you will have a pretty good idea why it is difficult to describe atheists as a group. Positive Atheism, as we advocate it here, is a specific form of atheism, a philosophy that is atheistic and which advocates specific ethics in addition to the rejection of god claims. Secular Humanism is similar in that it, too, advocates a specific system of ethics in addition to the rejection of god beliefs. Objectivism is another philosophy that adds to the core rejection of god beliefs. But you asked about atheism itself, so I will try to address your questions in the context of regular atheism, and also to show that some of your questions really have no specific answers.
Some atheists think the universe has always been here.
They are just one small group, though. Particle physicist Victor J. Stenger explained how this could have happened naturally, without any supernatural intervention, in our interview with him. Many of us, though, don't even care how the universe formed or how life came to be. Many of us are fascinated by what science currently has to say about these things, but most of us are more interested in seeing science work on curing disease and making equipment that is more energy efficient and things of that nature. Most of us would much rather go to a ball game or see a film or hear a rock and roll show than attend a lecture on the latest developments in the Inflationary Big Bang Theory.