I don't know how hot it gets in Auckland in summer (I've only ever been to NZ in winter!) but if it gets hot, then go for a pale colour. Dark roofs should be kept for cold places!

Something like this would be great!

Hey there. Go for a cooler colour palette and draw the eye to a focal point at the end of the hallway, a console table, artwork, a mirror etc. A cooler paint colour helps the small space visually recede. In terms of the doors, going slighter darker will again make the space feel bigger. Go half a shade lighter on the low ceiling than the walls, using the same colour, rather than bright white, which will look dirty in the low light. Good luck!

There is a lot of paste and size residue still on the walls. Washing and scraping helps but it still feels like it's there. Would a good sanding be sufficent or do I need to wash all the paste off before painting?