Look forward seeing the finished article! Pretty much what you doing is what I done to mine, facelifted bumper, sideskirts and clean rear valance with lower gloss black finish! The only difference is I went with the GT Sport frontend on mine rather than GTI that you're going for.
If you're upgrading the wheels then you should consider lowering it if you're on stock springs otherwise it would look a bit off (my car looks like a 4x4 at the moment with my BBS'
, hoping to get it lowered within the week or two once I get my Koni dampers). It doesn't have to be extreme, given that it's a daily you probably want the lowering springs and uprated damper combo to keep it relatively comfy.