Depending on your time zone, PHP 7 was finally released on 3rd/4th of December 2015. Even though the general recommendation for production servers is to wait for a little bit and gather some experiences before upgrading, some of us want to jump right on and upgrade to PHP 7.
WordPress requires write access to one directory, and that one directory only: the directory returned by wp_upload_dir(). By default, this is /wp-content/upload, but it can be configured to anything that is beneath your document root, like /media, if you want to.
As I’m writing this, the calendar shows April 14 2015. According to the PHP 7.0 timeline, it has a projected release date of November 2015. But if you want to try it out (to check out the speed), you can already do so.