You have to buy it offline, or you can ask the hotel you booked in advance to help buy it on your behalf.
Yes, student tickets must be purchased offline with your student ID.
Yes, if you join a group, you can ask the group leader to buy it for you, or you can go to the scenic spot and buy it offline yourself.
Yes, you only need to show your student ID to purchase when entering fee-based scenic spots.
Yes. For student tickets, students need to bring their student ID to buy them offline.