1. With the ADIRUs off, there can't be any GNSS position at the GNSS page of the FMS.
"For initialization purpose and GNSS position validation, the MMRs receive the last valid A/C position from the ADIRS through the Aeronautical Radio Incorporated (ARINC) 429 bus. Once initialized, each MMR sends the GNSS calculated data (GNSS A/C position, etc.) through the ARINC 429 to each Air Data/Inertial Reference Unit (ADIRU)."
2. The altitude of the GNSS should indicate the AC altitude. Currently at EDDL it should be ~ 148ft