I like nr.4 more, but with a twist: It seams to me like the universe craves complexity wherever it can produce it. Life is extremely complex, so that is the result of that craving. Everywhere there is a chance to sustain life (not only the one type we know of) life will form or be brought to and remain (eventually, but billions of years is a long time). Yes, I believe even in a star.
We will have some answers to some of these theories in the next decades, and better answers in about 100 years but all regarding life in our solar system. Even if it turns out that there is no trace of life past or present in the Sol system other than the Earth, it won't tell us much about life elsewhere.
Edit: That craving might be god's work though or even god himself.
