How to get firmware version of zwave device...?

You are right, if you know where to look:

              <version>2</version>
              <instances>1</instances>
              <control>false</control>
              <versionSupported>2</versionSupported>
              <libraryType>LIB_SLAVE_ROUTING</libraryType>
              <protocolVersion>4.5</protocolVersion>
              <applicationVersion>2.1</applicationVersion>
              <hardwareVersion>1</hardwareVersion>

Thanx for your explanation and confirmation!