Originally Posted by zaphod234
1. Can Calibre change the metadata (author, title, etc.) in the original ebook file (Word, PDF, epub, etc.)?
The "original ebook file" is never touched by Calibre. Calibre always makes a copy of it and stores the copy. The copy is normally an identical copy (html files are converted to utf-8 character encoding.) That original copy is not normally changed. However, for you to use that copy, Calibre must export it, and during the export process, it does get changed. If you Save to Disk, the metadata is updated. If you Send to Device to send it to an E-reader, the metadata is updated. If you Convert to another format, metadata is added to the new format. If you really want the metadata changed in the copy stored in Calibre's library, do a Convert to the same format.
(BTW, Calibre does not handle Word documents, .doc format, other than to just store it.)