The people who have worked on the particular code in front of you are few and far between. Fewer still are the people who can put the code in front of you together with what you want to do (probably numbering 1, yourself included). Your best bet is to go to the application's web site and see if they have developer documentation or a developer mailing list you can subscribe to. Don't forget that developers are probably working on their own projects and they are likely to tell you to RTFS. There is no substitute for reading and understanding the source code of an app.