In my book I make a big point of defining "qtr profiles" and "qtr curves" in the way they are used in discussing the calibration process. They really are different things, and new users are often confused when they see the terms being used interchangeably—it is like trying to communicate in two different languages. Here couple of things that I hope clarify it.
The "curves" are only in the .quad file, which are represented by sets of individual integers for each of the steps in the tonal scale. The curves are the result of the install script processing the information in the ink descriptor file (the profile).
If you are on a Mac and have installed final version of the linearized qdif file you can remove it from the profiles folder in the QuadToneRip applications folder. If you remove the qdif file from the profiles folder it won't rebuild the quad file every time the install script is run, but you will still be able to print with that set of quad curves. It isn't important, but it might save a few seconds each time you run it. You can remove all the profiles for papers that you are not going to use (and remove the .quad files from their respective folders too). That just helps keep the print dialog boxes a little less cluttered and less searching for the curves you really want to use.
Hope that helps,
Richard Boutwell