Lightroom edits exist in the Lightroom catalog*, the image themselves are untouched. Edits can, optionally, also be recorded in XMP sidecar files, which are files associated with the RAW images and typically are stored in the same directory as the images. Where your Lightroom catalog exists is dependent on where you decided it should be, as Lightroom doesn't care.

Lightroom handles image location changes every elegantly, and isn't all that bothered when it can not find the image files, which you will know as the Library module will show a series of "?" showing its not sure where the files are. If you restore images in a different location, or on a different drive, you simply tell Lightroom where those images are (right click on a folder and choose "update folder location") and Lightroom will update its links to those images.

This makes it very simple to move your images to other harddrives, rename a hard drive, whatever, as its only a one or two click change in Lightroom.

So, I wouldn't worry about 'marrying' your catalog and images, as this is a standard, simple task in Lightroom. Worry more about keeping backups (note the plural) of both your LR catalog and the images.

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**technically in metadata, which is what is stored in the Lightroom catalog, as well as in other image types like DNG and PSD, which have provisions for storing metadata in the file itself. 'XMP sidecar' is a metadata file*