When creating a project from local media, or via a URL, you'll notice that Advanced options are available. (These are also available on the Project page, via "Edit project info" from the dropdown menu.)
Notes: Here, you can add project specific notes, which are available to anyone who has access to the project. URLs are formatted as hyperlinks, so you can link to resources very easily – a brief for the linguists, for instance.
Due date: You have the option to specify a project due date, or deadline. You can filter by Due date in the Project list view.
Frame rate: CaptionHub usually does an excellent job of detecting a video's frame rate. If you need to override that frame rate for any reason, then you're able to do so here. CaptionHub does not normally detect 29.97 non-drop frame, for instance.
Timecode SMPTE start: Here, you're able to specify a timecode offset for your media.
Lock timeline for linguists: In some scenarios, you may not want your linguists to have the ability to adjust timings. Enabling this checkbox means that they're unable to do this.