@: SakuraKun
Hey, glad to see you taking on a Cortana cosplay!
I do like most of your ideas so far, mainly the LEDs.
It's funny you contacted me, I was also contacted by another member about a "Cortana tutorial" or step by step process of how I did mine. If I might say, you may want to hold off on getting it done by Halloween. If you haven't ordered a suit, it probably won't be there in time, let alone to work on it. Just saying.
That, and I am working on a step by step guide, with where is the best places to get the things you need, along with tips, links, etc. It's taking alot longer than I originally thought, mainly due to me being overwhelmed by work and commissions, but it will be done sometime in the next week. It should help answer most if not any/all questions you might have, and help give you some ideas.