1. The Elite will not connect to the HB ...
2. You do not need to remove the Navionics card to record AutoChart Live data to the internal memory ...
3. AutoChart Live just needs a 2d source so the US2 should work ...
4. You would need to insert a Zero Line card in the HELIX unit to transfer the AutoChart Live data to the Zero Line card... and then import that into AutoChart or AutoChart PRO PC software to format the AutoChart Live data into LakeMaster mapping data that can be read by the 899 ...
5. Ethernet between the HELIX and the 899 will allow sharing of waypoints, accessories, and "like" Sonar data (CHIRP on the HELIX would have to be shut off to share Sonar) ...
6. NMEA would gain your setup nothing ...
Rickie