You will just have to see once you get the springs on for what you need to get the alignment in spec. But you might get lucky and not need anything or maybe just deal with a little uneven tire wear. And you should get new struts since you will have the suspension apart anyway and your old struts are probably worn out or there will be a benefit to their replacement. The kyb gr-2s are nice if you are on a budget. Are you doing this whole thing yourself?

what do the struts do? and how do i tell if my current struts are shot?

me and my dad are going to do it, he lowered my last supra, and now that i want to lower this one i figured i would learn as much as possible about doing it lol.