Was john Harvard the dean of the university?

Yes. John Harvard (1607-1638) gave half of his money and his personal library to the school when it was first built. In return, the school was named after him.

Yes, John Adams attended Harvard University at age 16.

He wanted to be a merchant and/or a statesman but once he graduated he had a bachelor's degree.

He joined the navy and then worked as a journalist for awhile until he was elected to Congress,

Because John Harvard was the university's first benefactor, he also left his library and part of his state to the university when he dies.