For chair scoot and sit space, I'd follow the guidelines for a rug - 4' all around. Then you want to be able to navigate around the table while people are seated, so add another 18" all around. Are you locating the table at the end of the galley? Maybe you could use a banquette on one side or in the corner https://www.houzz.com/photos/3rd-street-bungalow-traditional-kitchen-austin-phvw-vp~214425

Carpets would be the preferred choice over tiles.

New Zealand! You live in paradise! Porch paint is specially made paint for wooden porches or decks. Its not a stain but an actual hard wearing & weather resistant paint that allows the wood texture to show through. Its safe for indoor or outdoor use. It is self priming & self sealing. I have used porch paint for wood paneling & kitchen cabinets & when remodeling a staircase formerly covered with carpet. It comes oil based or water based acrylic. I prefer oil based for a glossy easy to clean finish for a wooden table top. You may check your local home improvement/hardware store or paint store. I use Glidden Porch Paint. Takes me only 2 coats for white & the oil based goes on easily with a roller. Dries quickly too. Good luck!

If you are seeking a truly open feel to the floor plan you have shared, then using one material in the mail living area is the best approach to making this space feel truly open. Using a variety of materials on flooring chops up the space and decreases the visual footprint. I would suggest using wood, tile, or if you are on a tight budget laminated flooring for the living/dining/kitchen. Then use carpet in the more intimate spaces; bedrooms and possibly hallway. Save the tile for the bathrooms.