I had a similar conversation about this with a friend of mine last weekend. With the Eibach Pro Kit you get about a 1" drop. When I put mine in, I was focused on having to get new upper strut mounts to adjust for caster/camber. Ended up with just the 1" drop, I remained in good alignment. With that said, I'm assuming you have 05-10 model shocks listed to mate with the strut mounts (as your car appears to be a 14). You can very likely save a few bucks on the GT500 strut mounts unless you just want to look at them installed. Not saying that to pick. I've done overkill stuff on my ride just because "I wanted it there" not because I really needed it. But you can save a few bucks there if needed.
I haven't heard anything about the Eibach Pro-Dampers but am anxious to from your experience. Have Koni oranges here and wish I had it to do over. The other items you have listed, I've installed here and am very pleased. All except for the upper control arm. Unless you have a one piece drive shaft, I wouldn't sweat that. Time/money/labor not worth it because your pinion angle won't be changed much from 1" drop. To quote a friend, "a full tank of gas, two bags of groceries and your spare tire cause more pinion angle change than a little drop."
2016 Mustang Ecoboost Premium, Performance Package: Roush Quarter Window Scoops; Roush Jackal Rear Spoiler; Modded GT Wire Mesh Grilles; Eibach Pro-Kit Springs; Mishimoto Oil Separator; MAPerformance CAI; MBRP XP Catbacks; Drilled and Slotted Brake Rotors; BAMA 93R Tune; Royal Purple juice in everything!