As for how the practical puppet was used on set; the Mark Hamill interview only says he "ran it around the shop", which doesn't say anything about having r/c controls for the thing.
More likely BB-8 is a ball on a stick with the axle entering the ball on the off-camera side and a rod coming up the far-side to support and puppeteer the head. That way a puppeteer could just run it along the ground wherever they want it to go, and then production erases the rods in post. That would be considered a practical puppet by movie making definitions.
We prefer to keep it simple and low-tech when we make props and puppets for movies and TV. It's cheaper, quicker to make and more reliable on set. The last thing an operator wants to have happen is the Director and crew all waiting around for him to sort out some glitchy, complex unit while the money meter is running. We only use fancier things when there is no other way. It's hard for a ball-on-a-stick to go wrong.