Here is a really good StackOverFlow thread that explains some concepts - such as how sling treats content under /content and /apps. Also the difference between sling:resourceType and sling:resourceSuperType.
http://stackoverflow.com/questions/22708055/how-does-apache-sling-script-resolving-rules-work
Also - watch this Ask the Experts session:
http://scottsdigitalcommunity.blogspot.ca/2015/05/may-session-of-aem-ask-community-experts.html
