I feel like a total noob posting here. I know CSS, HTML, and XML pretty well but have always avoided JS. I know very little javascript and recently started a Lynda.com course
Since DocsList is deprecated, currently you can make a copy of a file using the following code:
DocsList
File file=DriveApp.getFileById(fileId).makeCopy(fileName, folder);
where fileId can be obtained as explained in the answer by Arun Nagarajan.
fileId