Custom Lists

We have a new WordPress site, and it is amazing how much we can do with so little code. We have a few areas where we need to access a web service or database to display some data in a custom list. In my Custom App Dev role, that is pretty straight forward, and it looks like I can modify the php to get and dispay the data that I want. I am worried that the next time our marketing folks modify some content that any custom work that I have done would get wiped out. Seems to me that the best way to handle displaying custom data is to create my own custom plug in. Is that the best way to go to display some custom list data, and be protected from getting the code wiped out? Thoughts?

I have been trying to read up and research this question yesterday and today, but I can’t find a good answer. I apologize for asking such a basic question.