How is the without-visa-required process?

Hello, my name is Nancy, I'm currently studying in Shanghai as an exchange student. I'm Indonesian, but hand student schengen visa since I'm listed as student in Austria. I've checked some informations about visiting Hongkong-Macau. In fact as Indonesian, I dont need any type to visit the countries within 30days.
1. How does it work? Is it ok just to entry the country without prepare any documents (only show my passport)?
2. My Chinese type is type X2 (6 months) for only one time entry, does it mean that I cant entry the country anymore if I dont change my type? because the lecturer in Fudan told me, that I'm allowed to leave the country and back again only once without having multiple entries visa, is that right? how is the procedure? thanks before.