Therefore, it is highly likely that there are extraterrestial planets on which life exists. The universe is many billions of years old. Therefore, some extraterrestial life should be older than life on earth. Therefore, it is likely that there is some extraterrestial intelligent life. 9 depends on an unacceptable assumption that the age of life on a planet is correllated with the probability that the life on that planet is intelligent.
All premises seem relevant.
They all concern the probability that there is intelligent extraterrestial life. No fallacies of relevance are present. The argument is inductively strong. If the premises were true, it would be improbable that the conclusion was false. This argument does not meet the ARG conditions due to failure of the A condition.