Hi Carolyn, I would suggest any food safe oil just in case you might cut on it. You can find this kind of product in any kitchen store. You can also order it online like this product: https://www.amazon.com/John-Boos-MYSB-Mystery-Butcher/dp/B00063QPYQ . Hope it help :)

adding furniture always gives a much better idea of available space and bed 4 is much too small for a living area although bed 3 without a wall and wardrobe could be used for a small TV room to open up the long hallway but i've moved bed 2 to make a MPR, added generous ceiling height biw in every bedroom (to include general storage as well as personal items) and simplified the bathrooms and the wide vanities can be used for linen..assuming that there will be a restriction of total floor area to block size i've kept this variation of your plan to 60% of the total area and think highlight windows on the south and tall wide windows above 750 off the floor on the north will allow plenty of northern light and still allow easy furniture placement, the MPR could have a western window to make the room more comfortable in cold weather and external blinds to exclude hot afternoon sun and shade blinds on the outside of the verandah would screen the sliding door but i would omit the external laundry door and the "pantry wall" as shown in Dreamers photo of my own pantry can be included inside wall cavities and needs only about 15cms depth for very useful storage

Talking about a complex roof design, yes that will increase costs. It will also be a nightmare for solar PV panels (which should be an important consideration for all homes nowadays). Not only will the complex roof increase the complexity & cost of solar installation. The results will look pretty terrible too - if that's an issue - as rectangular panels don't fit well on triangles & trapezoids. One reason for the complex roof - other than Australia's love of hip & valley roofs - is the complex floorplan. A complex shapes footprint will lead to a complex roof. Talking about trying to keep costs down, as you've started, a complex footprint not only results in a complex, costly roof. Complex footprints will increase building costs in other ways. They'll result in a larger external surface area. As external walls are more costly than internal walls, larger external surface areas increase cost. Each corner will increase cost. There's a lot of corners in this building. There's unusual angles, which will also greatly increase costs. On a sloping block a large footprint will lead to much more cutting & filling, much more retaining. I'm not expert, but I'd weight up the costs of a large single storey home on a sloping block, verses a much simpler shaped rectangular home, with a much smaller footprint, double storey at the rear. It may turn out that in this case a split level home - with increased comfort & far more northern light to living areas, & views to the south in many rooms - may be worth an additional investment. In any case, is be looking at reducing the size of the build, of costs are an issue. It will be much better for the environment in any case. Looking to utilise multi-purpose rooms, such as a home theatre that doubles as a guest room. Limiting hallway space, dead space in some people's books, removing the scullery (I personally hate these things). I think good design is far more important than having a home that is larger than needed.

Also if i can avoid moving air con for now that would be great. The next phase of reno will be to take down the wall between lounges and put aircon on the front wall of the lounge as it's the only other outside wall it can go on. Here might be my plan for now. I'll put the kitchen in place and figure out if i need to add more storage to office area. Will add range hood and a few long open shelves like in the image below (and is also the look i'm going for decor wise)