Questions---Specific: IDE-like functionality; General: how-to resources

Background: In my opinion, one of the greatest things about emacs is the everything-plus-kitchen-sink functionality one can access through the editor and associated packages in a unified fashion. After years of using emacsen, I'm relatively well versed in the core functionality pertaining to editing chunks of text. When I encounter a repetitive or unwieldy task, I try to learn how to streamline things by reading up on some unfamiliar feature or mode or package to make my life easier. Sometimes, I know what concept I'm looking for but not where to find the implementation. The concept index is a good start, but often doesn't have the breadth of coverage I need. General question: Is there a resource, perhaps on the web, where I can search by what I want to do, and find out how others are doing it? Specific question: I'm editing some code in C. I really like the ClearCase integration, but I'm looking for some additional IDE-like functionality. Specifically, I'd like for XEmacs to take me to the soure for a function call currently under the point, and I'd like something like tab completion for variables and functions accessible from my current scope. I know this must be a solved problem, but I haven't found this functionality so far by browsing the documentation. This inability to find something I know must be there is the driving force for my general question above. Thanks in advance, Tom