Hire a lawyer too while you are at it.......Nah, just joking(I hope).
Sounds like you are well on your way to a decent set up. EV makes really great sounding cabs and the mixer seems like a good match/choice.
The guys over at MTU forums can be very helpful as far as using their software, and one or two of them can suggest the best external sound card, but first make sure yours ain't good enuff....It just might surprize you.
Watch for ground loops that cause hum, and poor quality cable patches that cause hiss....Many times laptop users will discover that they pick up an annoying 60Hz hum only when the laptop is plugged in to 110VAC, but not when operating off the battery. They usually fix the hum by clipping the ground prong at the laptop power cord.(please you guys don't bother to scream how that might be unsafe. I'm sure all of us have read the warnings already that come with everything electrical now-a-days).