I have recently started working on an eCommerce site for a company and they have selected Magento 1.4.0 to run their store. I have spent most of my PHP "career" working with various MVC frameworks (even Zend with Magento is supposed to be based on) but the complexity of Magento seems to be on another level with no seemingly good resources to look to for help.
Looking around the site I have seen suggestions for certain books to use as reference, but they all refer to Magento 1.2 or 1.3.
My goal is to develop for Magento in a way that I do not alter any of the base code so that the client can easily upgrade the version of Magento and just "drop in" my code and have it work. The current issue is how to properly use the layout/template breakdown correctly and how to add custom model/controller functionality to the application without hacking away at Magento's core code base.