Hello,
Our base dummy content can be imported only once. Even after theme installation, you can’t import it since it may break your current content. We suggest you simply reinstall WordPress from scratch and run the import again. Or if you just need a few pages you can import them manually via Dashboard -> Tools -> Import -> WordPress. Files for import can be found in the folder inc/dummy-content/.
Demo Import: https://xtemos.com/docs/woodmart/installation-process/#import-demo-content
Sorry to say that but not you can not only Import the Menu, but you can create the Menu by yourself by our Theme Documentation here: https://xtemos.com/docs/woodmart/adding-menu-site/
Kind Regards
Xtemos