I recently purchased some new gear and since it’s my first time to use a mixer rather than a controller I’m having some difficulty getting my head around the setup.
If possible I’d like to connect everything to my MacBook Pro via my soundcard so I can control Traktor or some other software in external mode, preferably with the highest sound quality possible and the ability to record sets, I have a few XLR and 1/4" cables.
What’s exactly troubling you? You have a soundcard that has 2x stereo outputs. You need 2 cables that have double rca connectors on both ends so you can connect it to your mixers line inputs. Connect your Yamaha monitors to your mixer’s outputs (either balanced or unbalanced rca, depending on cables you already have for them).
If those are CDJ 900 players, you can use them as single deck controllers for traktor by connecting them to your mac with usb cables and using HID mode. As happydan already pointed out, you can even use their own interfaces for sound output from Traktor thereby eliminating the need to use a separate soundcard.
If your only trouble is wanting to sound as best as possible you shouldn’t worry. No matter how you connect your gear (AudioHub or CDJ900 as soundcard/s, balanced or unbalanced cables for speakers) you won’t hear any difference in your room.