Where can I get cheap halal (= muslim) food?
Don't worry, there are plenty of take-away shops and restaurants serving halal food.
Any safe areas with a large muslim population?
Hmmm, that's currently a big issue in the Netherlands.
There are a few notorious areas in Amsterdam, but the city centre is not one of them. If you stay in the centre, you'll be fine. Just be aware of pickpockets!
Hostelworld is very full during Queensday. Can anyone tell me of some towns very close by that I could find a hotel in and take a train/bus to get to Amsterdam? There will be three of us.
Thanks again for the help.
You may want to check for vacancies with the nearby hostels in Haarlem or Heemskerk. The one in Heemskerk is quite cool, because it's a genuine castle. There are direct trains from both Haarlem (15 minutes) and Heemskerk (40 minutes) to Amsterdam.