1) appointment: 2-3 days in advance for my sister's case;
2) days: you go back after 3:00 or 4:00 pm at the same day to get your passport if issued a visa;
3) Parents' visa: it has been very easy for my parents even the first they applied. They tend to believe that parents will not stay in the United States. My only experience is, applied to any kind of visa, that you should try to apply for a visa in Chengdu if possible. It is the easiest place in China.