You export a CV or a report to PDF and send it off. The pages show only what you meant to share, but the file itself usually carries your name, the software you used and the time you last saved it.
The obvious place is the document properties, which hold the title, author, subject, keywords, the program that made the file and two dates. A second copy often sits in an XMP block, which can also record an editing history. Some design and office programs add private data to individual pages as well, and every comment carries the name of whoever wrote it.
Clearing only the properties, which is what many tools do, leaves your name readable in the other places. A proper clean-up covers all of them, and also removes the document ID, a fingerprint that links a file to its earlier versions.
The pages themselves are a different matter. If your name is typed into a header, a footer or the text of a comment, that is content, and it stays. Search the document for your name before you send anything sensitive.
No. The pages, text, images, links, bookmarks and form fields are left as they are.
It works, but a digital signature covers the whole file, so the signature stops being valid. Clean the document before you sign it.
Remove the password first with the Protect PDF tool, clean the file, then add a password again if you want one.