1: See quicklinks for D2 S8 install. I believe a A3 unit is a better fit because of the rounded upper corners.
2: Controller between seats will not have any control over RNS-E.
3: MFSW should work the same as it is CAN-based. Not sure about phone controls. search this site on MFSW for more details
4: Yes, you will need gps extension cable. See quicklinks for nene's RNS-E install in his RS6 (very similar to what you want to do)
Happy reading!!
2: Controller between seats will not have any control over RNS-E.
3: MFSW should work the same as it is CAN-based. Not sure about phone controls. search this site on MFSW for more details
4: Yes, you will need gps extension cable. See quicklinks for nene's RNS-E install in his RS6 (very similar to what you want to do)
Happy reading!!