Good you already have the adjustable panhard bar to keep the rear centered. Lowering has to done as a complete package, not just the springs.
With the lowering springs, YES, you would need to adjust the pinion angle, for which you need the Steeda adjustable upper 3rd link and adjustable rear lower control arm brackets (I recommend the Ford Performance bolt on vs Steeda welded on).
You would be now into front bumpsteer, for which Steeda has the bumpsteer parts kit, then adjustable front swaybar and adjustable front end links
And time to replace the heavy OEM radiator lower support.
And, if you are still using the OEM 2 piece drive shaft, this is the time to get a 1 piece aluminium drive shaft.
Get it all dialed in together.
Beware the unintented consequences of vehicle modifications. I hate paying for labor twice. And find a competant mechanic.