Hi!
You will get some hurdle type questions at the start, make sure you dont spend any time at all on them (like what team would you like to experience or what other office than your main preference), they will let you know when the 'real' questions start.
For the main questions, there is about 5, I would suggest about 2 minutes for each, just because for me and some other people I know they do stop you if you are spending too much time on one question.
Hopefully this helps, good luck!