If the front can't be aligned, then yes they are required. If it can be, then no.
As for the pinion alignment, as soon as you take it for a drive you know if it needs shims. It'll have a vibration, if it doesn't, then you are probably fine.
At 7" you'll probably bottom out, you'll likely need a notch. And check your tail shaft to drive shaft engagement, you may need to shorten the driveshaft. Or everytime you hit a bump the suspension could be shoving the driveshaft into the tail housing, eventually this will break something.
And does rough countrys lowing kit, still mount the front strut under the lower control arm? If so, I'd get belltech drop struts and get rid of that garbage.