How early should I book my IELTS test slot?

Usually, the IELTS paper test is only on Thursdays and Saturdays. But the computer-delivered IELTS test often has slots on Sundays in big cities. You will get to know about the IELTS available dates while booking the slot only. 

Yes, A valid passport is mandatory. You need to upload a scan when you book and bring the original passport on the IELTS exam day. No other ID is accepted.

Yes, if you book IELTS on paper, you can often pick your Speaking slot during registration. For the computer test, the speaking part is usually on the same day or very close to your main test date.

Not always. IELTS Academic is available on all 48 paper dates. However, General Training is usually only available on 24 dates (about twice a month) for the paper format. On computer, both are available daily.

The university does not have a specific requirement of IELTS scores. The requirement can vary for different courses. It generally ranges between 7.0-8.0 for most courses. Some courses may also ask for 8.5. Students are advised to check the course page for the course they wish to pursue.

For Graduate courses, a score of 8.0 is usually required. Students with a IELTS score less than that, a TOEFL Speaking score less than 27, or DET score less than 125, have to take a language test at Princeton University USA.