You can copy all objects from a document to a specific section in another document of the project by selecting the copied objects, pressing CTRL+C shortcut, selecting the target section and pressing CTRL+V shortcut.
If you want to reuse a document in another project then save the document as a Document Template and open it in the target project. ReqView creates a new document keeping the document hierarchy, section headings, text description of objects and value of custom attributes and document object attachments. Note that Document Templates do not store object ID, discussion, history nor any traceability links.
For more information see Requirements Projects > Document Templates documentation section.