All Applications on OS X use the system clipboard. The standard for most applications is on the edit menu where you will find copy, paste, and paste and match style. The keyboard shortcuts are there too.
Pages (any version) is not a true Desktop Publishing application and will not replace MS Publisher. I would recommend Swift Publisher 3 in the App Store, or possibly iStudio Publisher. Both are reasonably priced.
If you need to open .pub files on the Mac, I suggest you download the lastest free copy of LibreOffice, which will open any Publisher file ever created. It won't be perfect, but sufficient to see your layout.