I fitted it today took about 30 minutes or so, didn't need to use a coat-hanger just the good old stick your hands through and play 'reach the cable'
it's generally a very easy job, and thanks to the OP some nice tactics such as removing handles to get a bit more access
I used the factory VW mic from Kufatec for a completely OEM install, you can get it here;
http://www.kufatec.de/shop/en/Volkswagen/Golf-6-5K/Wiring-Microphone-for-VW-RNS-315-Bluetooth-OnlyBasically, the mic sits in the hole in the interior light area (as the first page original poster shows) then you feed that Kufatec harness to the back of the RNS-315, and fit it inside the quad lock, code it and job done.
The RNS-315 does not have a Jack input for a mic, it uses the cable above which is to my knowledge only available from Kufatec, only takes a couple of days to arrive to be fair.
To fit the GPS antenna, best thing to do is undo the 2 screws underneath the heater vents (you will see them once you take the radio out) and then the whole heater vent unit pops out, there is a gap at the top, pop a bit of velcro or double sided tape on the bottom of the GPS and stick it to the top part, feed the wire down the side, nice and easy - replace heater vents, all good & lots of signal.
Only thing I will say, is that the RNS-315 does not seem to let me control the phone using the MFSW, pretty sure I can hang up using the phone button on the steering wheel, but cannot dial out or do anything like that, it all seems to be controlled purely through using the 315 interface.