I think it would be a bad idea to try and do a global find and replace for the word product and replace it with services. You should instead only change it in the areas of the site where it is visible to your. We do not have a method for converting these or finding all instances. It would be a custom process to look things over and find the words that you would like replaced then replace them in DW.
You should not be altering anything in the css js or php source in any of these files or you can loose functionality and cause the site to not work.