@Dddddd - While it appears to be mainly intended for external displays (it has replaced the DisplayPort), I remember seeing a quote somewhere from Panos Panay saying that the USB-C port does support charging, but not from all chargers, and I think at a slower rate than via their proprietary connector.
@dthrp - Just want to make it clear that because of the form factor, we suspect that it is a Max-Q variant of the GTX 1060 - although we couldn't find this specified in the press material (it all just said GTX 1060).
There is a chance that since the GTX 1060 is probably the only real heat producing part in the base that it might have a substantial cooling setup, which might allow a standard laptop GTX 1060 (maybe). It might also be a custom chip, a route which Microsoft has gone down before.
One of my colleagues is talking to a contact of his to try and get more information.