Blu-ray players support 7.1 audio formats and high-quality, lossless surround sound. While your high-def disc player and receiver may be able to decode these new surround sound formats, not all discs you play will take advantage of them.
You can choose to store your files on your Chromebook or online with a cloud-based file storage service like Google Drive. With Google Drive, your data is stored in Google's highly secure data centers. The Terms of Service make clear that what belongs to you stays yours..
As far as I know, Chrome Cast is compatible with iOS devices as well as Chrome and Android platforms only. Naturally, Windows Phone does not work with Chromecast, but an enterprising developer has started that process with an app called Tube Cast. It is only at version 1.0, so right now it only support initiating playback. Still, it opens the door for Windows Phone.