Gal will go grey (mid to dark grey) over 12 - 18 months. Initially VERY bright. The energy absorbed changes accordingly, from sub 5% absorbed to ~35%. Zinc maintains brightness for longer, though still suffers some dulling. Say 5% to 15% over time. This can be avoided by coating with a product called 'Sharkhide' metal protectant, used to stop aluminium boats oxidising. For there reasons many councils will not allow zinc or gal roofing (visual amenity, reflection issues), while making the houses more prone to requiring summer aircon at the same time. Surfmist Colorbond starts around 9% absorbed. If purely for energy reasons, a light colour might be the only option. If going dark, I would suggest at least doing the 'less aesthetically important' sides and rear in a light colour. Your call. If you go all dark, ensure you have good roof space ventilation for the summer that can be closed in the winter, and lots of well installed ceiling level insulation. Spray foam is more reliable over time than batts, see Spray It Solutions or similar (they have the Formaldahyde free Canadian Icenene foam).

Diluted Bleach solution or mould cleaner for paintwork to wash the wall but it probably is in the wall & cause could be a water leak somewhere ...gloves, mask & protect your skin. Sleep in another room if possible, mould is bad!

I'd stay away from putting any kind of detergent on it - it might look like it's cleaned it, but then the detergent sits in the underlay and continues to attract dirt as people subsequently walk over it. I know because my sister once had a bottle of shampoo burst in her bag while sitting on the carpet - the professional carpet cleaner said detergents were the worst. I'd get a professional in.

Hi there, because the new paint was Aqua Enamel, which means that you clean up with water not Turps. Water and metal don't like each other. If you have a good paint shop Inspirations etc near you have a chat to them so they can tell you what to use. What bad luck, all that hard work.