Could the universe have happened another way?

Yes, the universe could have happened with different initial conditions but then we wouldn't be here to discuss it. As to what you mean by "could the universe still be here?", you need to work on making sense.

That is a question that has occupied a lot of thought and discussion, yes. One aspect of particular interest to me has been the thoughts concerning how extraordinarily fortunate we are to exist in a universe which is so ideally suited for our existence, and how a different perspective shows that for us to be here to appreciate this "divine" or ideal condition is simply the result that unless the situation was ideal, there would be no one to appreciate the situation (we only exist because the circumstances are such that we can exist, not that the circumstances exist in ideal conditions to satisfy our needs).

And all of the fundamental laws of the universe are a reflection of this particular universe. whether there are other "universes" or not is an open question, but if our universe can appear, then it follows that other universes could also appear. There is nothing particularly unique about this universe that makes its appearance a favorable outcome, or so the thinking goes. If the fundamental forces that define how existence operates in this universe were different, the universe would be different, if that answers your question.

The multiverse crowd thinks there are as many as 10^500 universes in existence, a huge number that would account for just about every variation of universe we could imagine. If you could examine a million universes per second since the start of the big bang expansion over 13 billion years ago, you would still only have scratched the surface. If they are right, then the answer is yes, the Universe not only could but did happen in another way, every way you could think of, which sets the "finely tuned Universe" argument of religious believers on its ear. I don't know if *I* necessarily believe in the multiverse, since without observational evidence that to me seems tantamount to accepting it on faith, but it seems more plausible to me than does the existence of gods.

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I believe the answer is yes. However any changes in the fundamental values of the universe would alter it significantly; for example, if you altered the value of the nuclear weak or strong forces, protons and neutrons may not combine and there would be nothing but individual particles floating around. If the force of gravity was stronger, it would be totally different.

I'm a believer in the multiverse, because that could explain how karma works- every possible universe existing- you get the one you deserve.