1. You can ask for bone pieces from the butcher or may also use a whole chicken for best results. In Dubai I buy packs of chicken bone pieces from Lulu supermarket (you can find this in the fresh meat section)
2. If you do not want to spend 2 hours you can also pressure cook the ingredients for about 2 whistles and then simmer it for 10 minutes (provided you have a large enough pressure cooker)
3. I skip the celery if I don't have it. My family prefers stock made without it as it lends a different flavour to the stock.