Othello Questions Act I Scene I: Besides Roderigo telling Brabantio that his daughter has run off with the Moor

• Besides Roderigo telling  Brabantio that his daughter has run off with the Moor, how does he know it’s true?
• In lines 141-156, Iago states that Othello has already gone to the Cyprus wars.

“Another of his fathom they have none

To lead their business; in which regard,

Though I do hate him as I do hell-pains,

Yet, for necessity of present life,

I must show out a flag and sign of love,

Which is indeed but a sign.”

Why is he going too?

• When everyone exits scene I, what are they going to do?