You'll find some labels here and there, but it's never been the main focus of The Cover Project. The original purpose of the site was to create artwork to put old games in modern cases. (GBA into DS cases, PS1 into DVD cases, etc.) If the primary goal of the project was preservation, there would be a larger number of unmodified original scans of CD cases and classic game box art available on the main site.
There is a demand for box art because many (most) people discarded the original packaging for their old games and they exist today as loose cartridges. Labels generally stay with those cartridges so don't need replacing. While I agree that scanning and reproducing old labels is a worthy cause, there just isn't much interest unless a member gets a game with a damaged or missing label. When someone makes a label request, it is likely to be fulfilled, since anyone who owns the game in question most likely has the corresponding label, but not many people are producing labels, since the demand is so low.
As to dimensions, I don't think there's any templates or stickied threads on the subject, but the topic has come up here and there over the years throughout the forums. When I've needed to reproduce a label in the past, I've just downloaded labels that have already been created and based mine off those dimensions. Hope this helps!
