Nope my pony doesn't know anything about driving. He was ground driven once in his previous home where he turned around and attacked his trainer (I believe there was much more going on). So I don't know if this will be his thing, he does unmounted agility and has tons of fun with that. So if driving doesn't work for him that's OK. But I love to drive and I think with Clicker Training he'll learned to love driving too :)
I'm very careful about bridles! On the street my Belgian pulled his off once :O That was a panic, luckily he had a halter underneath and was tied. I'll look into those gullet straps. He'll have a whole new hair cut and fresh bridle path in a week or so
Thank you so much for all your help!