But I feel that I need a real mixer beyond the APC-40 especially because I am going to be DJing going between two macs very soon.
don't even try with 2 macs if you can't for now handle just one...
you don't need external mixer, live is a mixer too. Your apc40 IS designed to make what you wanna do inside live alone. Check apc40 and live videos, there are tons of useful threads on this forum alone too
The allen heath EQ is indeed cool but live's EQs are great too once you're familiar with' em.
Live and your actual gear is all what you need, just practice, test, and watch tons of useful tutorial videos