In Edge and Vibe right? At least it wasn't a thing in the club and lab a year ago...
Yes they're free, like anything with the kids clubs (nursery upwards) anything they do or come out with from the clubs are free (after the deposit for the Oceaneer band if in those clubs)
No they don't make their own, they maybe be able to request some or get certain ones made but it's CM that have to make them as they're essentially serving food so certain rules come into play. They're usually pretty simple: chocolate, vanilla, berries, mango...
It's basically a time to hang out with smoothies being offered.