You may need to take the car in to get it scanned by Ford.. it's hard to say with no diagnostic codes. Another person recently posted similar .. maybe transmission issue or if you are lucky maybe a brake switch ?
I say because it's bucking without you hitting the brake but it's all speculation until you get some codes.
The hybrid battery gets recharged every time you drive it. Car switches back and forth between battery and gas engine depending how you are driving.
Hybrid battery should last the life of the vehicle.