How old do you have to be to be president of Saudi Arabia?
Saudi Arabia is a Kingdom and is therefore ruled by a King. There is no President.
Has Barack Obama been to Saudi Arabia?
Yes and no. President Obama did visit Saudi Arabia, as well as several other countries, as part of a Middle East diplomatic visit in 2009; similarly, King Abdullah of Saudi Arabia came to the USA and visited the president. If you are asking whether President Obama visited Mecca, he did not; he only visited with the leaders of the Saudi government, as President Bush did in the previous administration.
What are the connections between President Obama and King Abdul?
I don't know if you are referring to King Abdullah of Saudi Arabia. If you are, it is not President Obama, but rather, President Bush who had close ties and longstanding friendships with the royal family of Saudi Arabia. On the other hand, President Obama has maintained cordial relations with the Saudi leadership, as most other American presidents have.