I only trade futures, so I have no idea about bonds and the interest, but I imagine interest are treated as foreign income, so I don't think there are taxes on that.
Also there is no withholding on foreign dividends in Cyprus.
Of course if you generate dividends in the US you're subject to the US withholding rate, which is 15% based on the double tax treaty the US has with Cyprus.
No need for the Non-dom.
Hope that helps..