Depending on the color your going with on the exterior, if you keep it red or another darker toned color, I'd go lighter almost honey on the floors; knotty pine? I have always wanted to redo a barn into a modern/rustic home!

Tile is still the best thing for a walk-in shower to be waterproof. Neither the cork or hardwood will be. Think about installing a radiant floor under the tile like Sharon recommended. I like the NuHeat Radiant floor system the best.

I have just taken a couple more pictures (excuse the untidy house) from the stairs. As you can see it's an open plan area that isn't that big but very high ceilings also in wood (Macrocarpa) with dark wooden beams. The house is surrounded by bush so quite a dark house. I initially considered a darker wood similar to the beams but not sure if that will make the house appear smaller / darker...I'm really not sure what to do!?!?!? Thanks

Thanks :) Yeah decided to go with tile. So sand cement is ok over existing tiles if I prep them first? Only problem is, the new pad can only be about 30mm at it's thickest (leaving up to 15mm for tiles) otherwise it'll end up being higher than the hallway floor. So I either need to make the fall shallower or not bother with the waste and make it all level. If I made it level, could I use levelling compound at that thickness or would deck mud/sand cement be the best option? Also, should I be putting in mesh for strength? (I know I should (and will) ask the local hardware what they suggest, but it's great to have suggestions from the Houzz community also)