If the ceilings are low, go for a slightly lighter tone - this will effectively heighten your ceilings - also pale colours push the walls back. So perhaps not white but a pale grey, cream or beige.

And the seating areas are different, don't try to make it look like one area. I would put minimal ( if any) teal around the black sofa. Do your dining room. Then give you living room the same respect, it is it's own space

A small sink would fit in the second floor plan w/c. its 2.8mx 1.4m so definitely enough room. If we use the last floor plan with separate w/c then it opens up the bathroom to be 2.7mx 3.2m which for New Zealand standards is a big bathroom for a shower, bath and vanity. I'm still trying to decide if the space for the dining and kitchen areas are big enough?

A very simple layout keeping the floor space within the kitchen, the WIP takes up a lot of space with not much gain, The broom cupboard could be moved to the Laundry/entrance, narrow. If the wall has been bumped out to the eaves on the deck side giving an extra 300 depth to the kitchen you could make the island 2700 x 1200 and all drawers. The wall of narrow pantry will hold all pantry needs and more, no deep cupboards to dig into. cheers