Son of God

There are two important passages of major importance here. But there is enough that needs to be said about them that each requires its own page.

In John 5:18 we discover that by "calling God his own Father" in the mind of the Jews at Jesus day, and according to their manner of speaking "he was making himself the equal of God." Did they understand him rightly? Was this John's opinion? What did he mean by that?
In John 10:30 Jesus claims that "I and the Father are one." Later (v36) he uses the title "God's Son" as if it were equivalent to this statement. What does he mean by this?