Check your local building department as you'll most certainly need a building permit for this modification. Even if it's temporary. Personally I like louvre windows. You'll get good ventilation and the newer products are a world away from the old style ones.

If your block is facing North or West (within Australia) maintenance will be required to ensure movement is minimized. Timber doors are beautiful they just tend to be susceptible to sun damage. FYI Cutek is a great timber protector if you want to keep the natural look however you will need to keep applying year after year.

Both so close it doesn't matter. Aluminium is better if it's thermally broken.

We have the same challenge with those cream window frames. If you use window coverings (I will probably add warm white blinds and sheers) think about what they will look like from the outside as well. Stark white will look wrong with our style of home. I love plantation shutters, but again, can’t have them because they’d look terrible from outside.