Don't worry about the windows, both of my lexan windows bow in, though mine are worse than yours.
Also, learn from my mistake and make sure your oil tank is grounded or the sensor won't work
It took me a bit to realize my tank was fully isolated.
As for the lights I say go for the piaas even if you have to buy them still. The aesthetic difference and light stability are probably worth it.
Thanks for the tip on the gkn parts, I'm gonna raid their catalog for porsche 100mm fitments and see what I can find.