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.
Number of interviews: 2
Skype interview: no
Time between interviews: 30 minutes
Length of first interview: 1015 minutes; Length of second interview: 1015 minutes
Was as expected, the first interview was academic. They ask questions related to subject. The questions were
Second interview was more general, why you like the subject and what do you hope to do after uni. I was pretty calm, kept the interviews more as a conversation and less as a q&a I even threw in a joke.
For the test I used past papers.
Don’t think about it too much, once you are there waiting for interview I didn’t do any work just relaxed.