The Summit one is the front-mid one (same as the Tanabe and others), the GT Spec is the mid one - they can be used together...
I'd be very interested to see IF you genuinely notice a difference on the road with these ones, and not just saying you do because you slapped some cash down
Yeah if you're going to him, you might as well (although I personally really enjoy working on it now).
It's not just the torque/leverage, I've found that the action of the impact wrench doesn't put as much continuous torque onto the bolts, which as you may have found... snaps them sometimes
Depending where you are based, you could always use a self service garage with ramps (I've used Pit Start in Acton).