Underfloor heating to your main ensuite, shouldn't cost more that $1000 and if you manage the off peak usage it doesn't cost much to run in winter when you need…

For $3000, id say that is a bargain. Over the lifetime of your home, it will say you more than that, and add an additional value to your home for…

Have you thought about obscure glass louvres? Best for privacy, and natural ventilation.

Have you considered engineered flooring, glued down to and underlay? It will not have the expansion and contraction issues associated with battens and floor boards, and no need for nailing.