I like the timber doors. Stick with them! No, They're not popular at the moment but I'd say thats more due to the cost when compared to a mass produced coloured/laminated/painted door which would be milled MDF or melamine and the like. Solid timber is just that, solid timber not some manufactured timber of an unknown quality. I'd go for tiles every time on a floor in a wet area. Genuine marble as a splash back would be awesome in a laundry, get a price as you may be surprised as it's not a huge area. Tiling does add up quite quickly.....

what a gorgeous old house and well worth all the work ...based on assumed measurements my suggestion would be to keep the original windows, walls and ceilings and only change what is absolutely necessary for safety and convenience..the battens over the joins is part of the charm of the old girl and makes it easier to add extra sections of wall but be aware of asbestos issues...add doors between new powder room, laundry and kitchen but no door on the pantry (better ventilation in hot climates and keep the original window and/or a wire meshed opening behind the now stove) and use air tight vintage glass jars and tins for storage...new glass back door with horizontal bars to match old windows, reduce the opening between central space and kitchen just enough to create a narrow screen wall for the side of the fridge and the tall shallow shelves (free standing old bookshelf or narrow dresser for storage and display?) and relocate the corbells to suit the new opening..add very basic plain cabinets and white appliances and add bling with counters, central kitchen trolley and vintage dinnerware...accurate dimensions of all the walls and location of windows and doors would allow a more precise plan and please invest in new plain security flyscreens for doors and windows and use modern louvres wherever you need new windows

A floor plan is needed and where the solid door leads to and any other doors or fixtures in the room. It seems a waste of space if that is the only useable area in the room. Can you move doors?

Working with 2400, the following idea, a 3 bedroom unit would benefit from a separate toilet, you could add a recessed hand basin but a good looking laundry and sink would cover that.. If the toilet was moved back into what is the laundry cupboard this would give a possible window, this space would then be transferred into the bathroom as a linen cupboard it would also place the doorway into the toilet in a better position. Alternatively you could leave access to the toilet via the bathroom, still keeping the toilet moved back to enable a window/ or not The family bathroom would then have a decent vanity and bath with shower over. The ensuite would have a 1400 shower with a toilet backing onto the separate toilet which should allow for easier plumbing, plus an exterior window