This is very basic magento question i guess. I want to first get all the store categories, then loop through them to get their sub-categories and products and similarly continue till the last sub-category.

I will be using this in an external page having Mage::app() declared at the top of the page. I am not aware of the Magento API's(if thats wat they are called) to use to get this functionality.

Remember I am not using this in any of the templates, so something like getCurrentCategory() will not work here i guess.

Also please guide if there are any good resources to search for particular functionality in magento and API's to implement it, or am i doomed to go through their phpdoc to know the list of methods.

Any help here will be greatly appreciated, Thanks.