There are no CHIRP options for DN or VW or C4FM, so how should we best
"map" CHIRP memory column modes to the FT70?

I have no say in this but we should discuss if amending MODES in chirp_common.py is an option to allow for the new modes "DN" and "VW".

How is AMS handled in this radio? Is it a setting that is stored on a per-channel level? If so, I guess the driver should also be able to handle that, in order to maximize the "Fusion" experience...

Regards

Matt

Thanks. 
AMS on/off is stored per memory channel - will default to on and handled in memory extras. The radio settings store what AMS does, i.e TX Auto, TX DN, TX VW or TX FM. I don't think this finer control of AMS is stored per channel - but have not checked! DMR and DV are in the CHIRP list so adding C4FM seems logical. Then perhaps mem extras takes care of setting VW? 
Also need to look at how the data imports are handled as more repeaters support several modes, but can only - it seems report one. I have a particular interest in this as I am involved in the RepeaterBook project.

Regards
Nicolas