You can pretty much do anything with VCDS if you know what you are doing of course, I have been exchanging conversation with Ross-Tech who make VCDS software with data that I have submitted to them along with other VCDS owners from here they tell me in the next release they hope to include better support for the A1 with the long coding helper and labels at the moment A1 is supported but you really need to know what you are doing because the labels are not up to date in the current release.
As for cables, I suggest the genuine cable I know its expensive at about ÂŁ260 but it's well worth the investment as the third-party cables may well be compatible but if something goes wrong when programming your car you potentially run the risk of warranty problems and will not get any support from Ross-Tech for VCDS software. At least with a genuine cable you are covered by Ross-Tech because it has a genuine serial number on the cable.
I will have a play at some point with the fog lamps to see what the procedure is.
So far the following items work with VCDS reprogramming;
DRL dimming when turn signals are on can be deactivated
DRL's can be turned off permanently if required
Staging (Gauge Sweep) can be activated
Video in motion can be enabled
Seatbelt Chime can be deactivated
Xenon Headlamps can be adjusted for European driving
Hidden Menus can be enabled in MMI Plus
As for VAG Assist technicians usually they use Panasonic tough books with VAG DIS systems on them which have a SIM card in them that communicates data over a VPN back to Audi/VW they can adjust quite a lot with those laptops however I don't believe it has the full diagnostics like workshops have for updates etc.
Thanks,
Mark