I was also going to suggest that you drive around your area looking at any new builds, who's building them and what Architect/Design firm has been involved. You could introduce yourself to any builders that you felt you might be interested in working with, call the Architect etc to discuss. If you can find locals to do the Job that's a plus, if there are any problems they are on the spot to sort. One of our Houzzers had a very bad experience where the Structural Engineer changed something without consulting anyone which ended up causing a major problem and expensive to boot. As annb has rightly pointed out you don't need to employ the Architect for the complete job as this will be more expensive, if your builder is good at his job he will manage everything with your input. Architects plans can be more detailed/complicated and sometimes there may be the need for the builder to check back with him/her. Big plus is that you are building where you live and are able to keep tabs on how things are going, very exciting time for you and your family

There's a move away from gas to the extent that new suburbs where I live are not even being provided with gas mains. Evap cooling when we researched some time back required some windows open and I remember people complaining about that during last summer's smoke. Regardless of which systems you choose, I could not agree more with oklouise, start with good solar passive design and insulation, that's the most efficient way of reducing the reliance on and cost of heating and cooling systems.

You could paint the metal Monument, remove the timber frame, tile the wall and into the painted metal frame, I would also want a bind for night time use otherwise it looks and is cold. I have just seen your ducted floor vent?, so I don't think you could have an open shower running across the end of the bath room?

I have upgraded floor grills in aged bronze that work with the floor boards and are very unobtrusive. I would say that they are the most aesthetically pleasing option. For atmosphere you may be able to add an electric log-look fire to one of the fireplaces. Their appearance has improved dramatically over the last few years. I have a real log combustion fire in my fireplace. It is absolutely lovely to have on a winters day but does come with maintenance and is not practical for everyday use.