What if you’re going down a slight decline where you could normally coast and maintain your speed. Do you have to leave your foot on the pedal and waste battery?

It's not wasting battery if you have your pedal in the position where it's coasting, neither regenerating nor accelerating.

If you want to coast, you have to apply slight pressure to the accelerator. It doesn't use battery. It's a little weird at first, but you get used to it in a couple days, then it's second nature.

Its really intuitive, if you are going a little too fast you just let up the pressure on the pedal. You don't have to think about if it needs to use battery, regen or coast to maintain the speed you want. In that aspect its like using cruise control in other hybrids/ev.