Ironically, it's often hardly to complete a single major than a double. Because fulfillin a single major requires you to complete all the modules from that one major; even the ultra difficult ones. Whereas in a double major, you can choose all the easy ones form both majors and still complete the degree's requirements.

Having said that, a double major gives you more options with your career (I'm assuming that you will be choosing vastly different majors). To employers, it matters ZILCH!

Second question: Honours or masters?
Answer:
Do you plan to join the civil service? If yes, pursue 1st class honours. If no, don't bother. Honours has no value.

Masters also has little value if you have no work experience.