Hello,
The CTA section is managed from the customizer > Front Page > Call TO action.
If you chose to set the section using Page or the post then it will link to that particular page or the post. But if you chose to use the custom option then you can add the link in the field “Button Link”.
Screenshot: http://prntscr.com/ngjlr7
As for the color, you need to add the additional CSS so please mention the particular section that you want to change the color of so that we can provide the precise fix.
Thank you.