those islands yonder they are the …

1)  The first sentence refers to the fact that Sadao's father considered the islands which lay yonder or beyond were the stepping stones to Japan's future. This means that Japan had to explore its options outside of the country and produce talent well-acquainted with the world to put Japan on the global map. 

2) No one has the reigns to a person's future apart from the person himself. Our future depended on how we chose to make our lives and the decisions we took. Just as Sadao knew that his education was the most important thing in his life to be what his father wished him to be. He went to America at the age of twenty-two to learn all that could be learned of surgery and medicine. He came back at thirty before his father died not only as a famous surgeon but also as a scientist. He had participated in the process of shaping his future rather than take the tide take its course.