These useful functionalities don't seem to be in Windows Phone 10. Did I miss something, or do I have to use some other apps (like Shazam for the music search) ?
No, at least not yet and not even on the final WM10. If you have Cortana in your country you can ask her to id music or even shazam a song but the Vision and Music functions are currently not implemented which is a big shame as I you now need 2 more apps in your phone to perform these tasks (Shazam - SoundHound - Musicmatch.. and a QR reader like QR Scanner). Although the standalone apps' functionality far surpasses the previously inbuilt one, I hate when baked OS functionality is removed and I really hope it will be added in future versions.