Hello Cornelius,
I took the PMP exam this morning - and I can confirm that you can leave your computer for each of the two breaks. The clock for the exam time stops when you take your break and there is a separate 10-minute timer for the break (during which time you can do what you like

). Also, you can use the full exam time how you like - I had a lot more time to do the last 60 questions, as I didn't use the proportionate time during the first two 60-question periods.
One note of caution - the exam monitor did not like me looking out the window for an extended period of time during the exam - he warned me to keep my eyes on the screen

.
Also, I found the registration took longer than I expected - I would follow the Pearson OnVue advice of starting the exam check-in 30 minutes before the scheduled start. My laptop took nearly 5 minutes to display the exam screen after running the system checks, which was a little unnerving (I reported this to Pearson in the feedback).
Finally - Good luck to everyone taking the exam

. (I found it easier than the PrepCast simulator - just don't panic during the first few questions - it takes time to settle - and there is plenty of time in the exam to complete all the questions).
Best Regards,
Andrew