Absolutely. There are several mounts available (sold separately, of course) that can accommodate all of the above. And there is literally a helmet-compatible strap. Additionally, there is a reasonably priced (10-15$) attachment you can find on Amazon and other sites that allow you to use GoPro accessories. It isn't needed, but since GoPro has many options, in comparison to the handful offered by Sony, it would be a safe investment.
If he is into kayaking, this camera DOES come with a waterproof housing.
As far as downloading video to your phone, there is a 'Play Memories" app that you can download for free (QR code in the instruction manual).