2x interviews (20 mins)
1 biology based; other chemistry based
A level books & mock interview
Nope
Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
I had two interviews, with only
One interview was more biology based and one was more chemistry based (there was a form sent around previously where we could state our preferences). There were questions on experimental design and more specific subject related questions.
Generally reading around the subject, A-level revision books, other books, had a
Nope!