The kit shouldn't make too much trouble for you as far as groung clearance. The lip and design pieces don't go more than a quarter inch lower than stock. You'll be fine.
It's more an add-on bumper pieces, than a lip or facia kit.
As far as how low it can go...I'm pretty sure you can go until it's sitting on the ground, as long as you get your camber fixed and your rubber liner's gone.