When you Save To File ( non raw / raw [I know raw files get side cars, and maybe this is less likely] in Lightroom does this change the orientation slightly of all the photo image pixel information from it's original place in the file structure when you add new informational metadata to the file?
If you are talking about saving metadata to file, there are header records which are used for the XMP information. However, the image portion of your file is never changed by Lightroom, the pixels are never changed. This is one of Lightroom's great strengths, as compared to something like Photoshop, where you can accidentally or intentionally change the pixels in the file and lose the original forever; changing the original pixels cannot be done in Lightroom.
... if you are concerned about a photo file's fine crisp display or archival state, way into the future...50 years or more?
So, if the pixels are never changed, then this is not an issue.
Is this one of the reasons that digital asset management sometimes teaches or advises people to archive their original photos untouched, and use copies for Lightroom(with metadata)?
I don't why anyone is recommending this, as it is not necessary to work on a copy in Lightroom. Now, if it makes you feel better, and you have the disk space, you certainly CAN archive the original untouched image straight out of the camera, but it isn't necessary to do so with Lightroom.
Also, for backup purposes, you do need exact copies of your original photos and of your Lightroom catalog file (which perhaps is splitting hairs and playing word games, but I view this as distinct from archiving, backups are mandatory, archiving is not).
First of all, raw files get sidecar files IF you choose the option to create them. Otherwise, all adjustments made in Lightroom are saved in the catalog. In either case, the raw file remains unmodified. The main reason you need a backup copy of your raw images is to ensure that you have them when a hard drive crashes. The file structure for different cameras isn't necessarily different. But different camera models have different sensors that respond differently. That is why it is necessary to provide support for each camera model.
Just to emphasize, there is never any pixel information changed in Lightroom. The images are always in their pristine original state. If you open the original JPEG image into Photoshop, it is possible for Photoshop to make modifications to the pixel structure of the JPEG file. But if you open a raw file into Photoshop, the results of your Photoshop work will be saved to a new PSD or TIF file, depending on your Lightroom preference settings. In either case, the raw file remains completely unchanged.
Thank You Very Much, this is a real problem area for me.