Hi Kathryn,
Experiencing Magic Kingdom at any time of day is fun, but seeing it at night, all lit up, is truly a magical experience. I'm happy to hear that you plan to take advantage of those evening extra magic hours.
To answer your question, no, not all the attractions are open throughout those evening hours. Attractions such as Carousel of Progress, the PeopleMover, Jungle Cruise, and Tom Sawyer Island are typically not open late. Don't worry, though, there are still many rides that are open and the most popular ones, such as Space Mountain, Dumbo the Flying Elephant, Pirates of the Caribbean, and Haunted Mansion, tend to be available for those later times of the day. However, the rides and attractions open late could change or vary without prior notice.
My best advice would be to check a times guide when you enter the park that day or use the
My Disney Experience mobile app for the most up to date park times and information.
Have a wonderful trip!
~Allison L