Hi Usaghi,
1) In the data sheet, we specify to not connect the exposed pad to ground. We have been flip flopping on this exposed pad for a while. The latest recommendation that we have on all ADE78xx is that the exposed pad should be connected to ground. We added new ESD structures into the ADE7816. The response to ESD events is greatly improved. We can now recommend to connect the exposed pad to AGND and DGND. The data sheet will be modified to reflect this change. The change makes grounding the layout much easier.
2) At the moment there is no errata information for the ADE7816.
3) Since this is based on the 78xx 3-Phase hardware, the 3 voltage inputs from the 3-Phase parts are then used as current inputs for the ADE7816. There is no special criteria for these different current inputs, just be sure to note that D, E, F have the same IN connection.
4) ESD tests are done on the ADE7816 during our qualification process. In the final product to protect the inputs, diodes can be used as in the picture below.
5) Yes, a better resolution image is attached.
Best Regards,
Dlath