The mirror is part of a larger housing that holds sensors against the windscreen so there are a few wires going into it, i think its the sensors for auto lights and wipers, you may be able to remove the actual mirror as dont think the wires go into it but never really looked so i could be wrong, depends what you think looks better a pointless mirror or a pointless balljoint poking out of the housing, i removed the mirror on my T5 but that was a lot more compact as was a base van without all the electric gizmos.
Its up to you how you run the wire it is possible to tuck it into the rubber that runs down the door side of the A pillar you can also tuck it in to the front of the headlining to get acroos to the centre of the screen, it works and worse case it may work its way out, personally i ran it all in permanently but i had the A pillar and headlining off for other stuff so wasnt an issue, hardest bit will be where to get the feed from, the wiring kit should have a fusebox piggy back thingy that makes life a lot easier but getting to the fusebox is not so easy without taking a couple bits of trim off.
Personally i would remove the radio fascia trim (extremely tight to get going but does come off) and the small end panel that holds the passenger airbag switch, this will give you a route from A pillar rubber, across dash over top of glovebox then vertical drop from stereo area down to fusebox, you want to use the smaller of the two piggy back fuses and connect to the middle of the three top rows of fuses in the fusebox as this is igntion live so will stop/start the dashcam with key on/off.
Not so sure the easiest place to pick up a negative as the one i used is at the base of the passenger A pillar which is not accessable with out removing the whole pillar cover but TBH any exposed piece of body metalwork can be tapped onto for a -ve as long as its properly attached to the van structure
Any questions ask away
