Macbook specifications & new audio interface

Hey nice people, I haven’t done much recording for a while but will have much more opportunity soon so I’ve decided it’s time for an upgrade.

I use Cubase 7 (will probably upgrade soon), a load of IK plugins, EZDrummer, some NI keyboards, Garritan Personal Orchestra… At the moment I have a PC with a Q6600 quad-core processor (from 2008) and an M-Audio Delta 66.

I have an opportunity to upgrade my work Macbook but I’m wondering whether a dual-core i5 with 8GB RAM will be sufficient for Cubase plus my virtual instruments or whether quad-core is absolutely necessary.

Also I’ll need a new, inexpensive audio interface. I’m considering a Behringer FCA1616 - love all those channels - or maybe a Focusrite Scarlett 6i6. Any thoughts you might have on the Macbook and interface would be greatly appreciated.