Yes, booking is only a must for China Pavilion and the China Pavilion staff will send reservation ticket at the entrances in early morning. You can book in the reservation machines at the entrances to the expo. ONly 20 paviosions offer reservation services. The fact is there is always long waiting lines in the most popular pavilions. So, but night ticket to have a night in expo is a not bad. No fixed mac capacity in each pavilion. At the begining, China Pavilion allow 30000 people to visit in one day. It depends in each pavilions.