I sure would like to re-use some of my caption text in succeeding projects. Is there any way to navigate to the storage location for an earlier project and add them to the current one?
Generated media such as text is stored in the .vf file. There's no separate storage for it on your drive anywhere.
You can open up two instances of Vegas at the same time. Open your new project in one of them and an old project in the other. You can then highlight and copy from the old project and paste into the new one.
For a slightly more advanced method, you can save any particular text layout as a text media generator preset. This preset will then be available in the pulldown menu at the top of the text media window in any project. However, there's probably a limit to how many of these you want to keep around before that list becomes unwieldy.