Problems when I built my simple system

Yes, you would need to modify the IP (or put a wrapper around it) to have only one data vector instead of sink_real and sink_imag.

For the clocks, in the system that you made, they are both defined as extern. This means that they will both be inputs in your component, and it is up to your top level file to provide them, either through pins, or through a PLL that you add using the megawizard.

As an alternative, you can also add a PLL directly in the SOPC system to create the fastclk, and have only clk_0 as an input to your component.