Motorized scooters, historically powered by gas engines, and more recently electric motors, are self-propelled kick scooters capable of speeds of around 35 km/h.

请问老师：

1 historically powered by gas engines, and more recently electric motors 这是and连接的并列过去分词短语共同修饰名词Motorized scooters吗？句子是省略了powered by，完整是historically powered by gas engines, and more recently (powered by) electric motors，对吗？为什么要省略呢？

2 capable of speeds of around 35 km/h是形容词短语做后置定语修饰名词kick scooters吗？