My recomendations :)
1. Battery regulator - checked the battery level on MMI and it was at 100% with no issues
###clear the error and see if it comes back as its intermitent
2. Potentiometer - can I just order a new one and replace instead of cleaning it?
### potenciometer is build in in to central 2 vent unit , whole unit needs to be replaced. Mine broke 2 years ago and its not cousing any issues , i can send you more info on this tomorrow .Look at this on eBay http://www.ebay.co.uk/itm/132280456443
3. Some of those bulbs are actually working but still coming up as an error - just replace them with new ones?
### Common fault . Take the rear lights out , clean all connectors and plugs etc and spray some contact cleaner . Problem is bad earth . If its not helping then you need to twist the earth pin so its sitts better in the plug. Let me know i can send you picture where as it sorted my lights issues