I suspect to give a really indepth answer , we'd need a lot more info , such as load bearing walls , which ones can and which can't be easily moved or removed , ceiling heights , whether the verandas drop down floor height wise , whether they can be 'windowed' in ( I suspect they may be arches from that era ? , even things like getting under the house to move plumbing and other services . At a quick look , Option 1 looks better , but some things I wonder about -- the study looks large ? I assume the stairs are existing -- how is the headroom at the halfway 'turn' ? Downstairs shows double width stairs , upstairs single , which is fine unless there isn't sufficient headroom at the 'turn' . IF you decided to do only 1 bathroom downstairs , I'd be inclined to look at not having that cupboard in the hall outside the Master bedroom , make it a door so Bed 2 can use it as the bath entrance ( with a lock that is normally locked to stop accidents ) . I also wonder about going from double side doors into the dining room ( which you said are used by almost everyone -- I assume there is a driveway or path along that side of the house ? ) to a single door into the kitchen ? Practical , but may be annoying / offputting with time . It seems you are trying to move minimum walls , but it looks like a reasonable amount of compromises -- hard to judge or suggest without more info though

or even simpler actually, enclose the porch and move the toilet into that space, then just leave the laundry and shower where they are. If you don't mind a walk through the laundry bathroom? I think I'd also extend the decking out significantly so it wraps around the back of the laundry too. This is my favourite as it's actually a rather simple (and therefore inexpensive) reno. Just removing the wall around bed 3 and shifting the toilet and building the deck.

moving the stair doesnt help the existing upstairs if your plan is to not change much. the living area would reduce from 3.5 to 2.5m width and would limit options unless you want to use this space as office/playroom. the existing door would have to be relocated to bed 1 and the green line is an existing beam which looks to be tight on the 12th stair down which is usually the minimum head height clearance.

I was inspired by the block, which has excellent orientation for a house which is comfortable in the local climate while being good for the planet, thus my comment about the stars, I think that is more valuable than the emphasis on 30 squares. The rest is up to the occupants' requirements, about which I am increasingly confused. I love seeing what others come up with, but I always feel the best starting point is a clear explanation of the requirements.