Is there a way to make Qt Creator recognize TODO and FIXME comments, so that I can access a compiled list somewhere of all these comments?
Yes, go to Help / About Plugins... menu, under the Utilities section you will find the Todo plugin, so you simply have to enable it. After restarting Qt Creator you will see the To-Do Entries button on the bottom of the main window, which opens up a panel listing all TODO, FIXME and so on comments.
The plugin has some minor issues, the one I remember is that international characters are not displayed correctly, but in general it works quite well.