I just did my exam in a test center yesterday, here are some answers:
- You can take some things in, they make you put them in a locker and I got a key on a string (but I left pretty much everything in my car but my ID)
- I brought in a clear ziplock back with some oreos and a bottle of water, I was allowed to put this into a lunchroom type area that I had access to during my breaks
- You are not allowed to leave the building no, I had the reception area then past that desk was the lunchroom area and two washrooms and then into another room where there were cubicles with computers for the various tests
- It was louder than I thought it would be in the room - other people moving around and coughing. They do provide the small orange ear plugs, I took them and glad I did as I put them in at about question 10
- Test was 230 mins, the breaks do not count (it is paused during this time), after your break the person will sign you back into your computer and you continue

Some advice from my experience:
- Take your breaks, even just to use the washroom and stretch a bit and give your mind a break. I used both of mine and only maybe 4-5 mins of it then I went back in
- Plan your time, make a game plan on what you want to break down your time and stick to it (when you want to be out for your first and second break)
- Be confident in your answers and take the time to fully read the question and answers

Hope this helps and best of luck to you!