I don't think you can go wrong with a large timber door. The colour should contrast with the granite nicely and will even help soften all the colder surfaces. Have you seen any doors you like? https://www.houzz.com.au/products/front-doors-prbr0-br~t_10816

Your door supplier should have given you colour swatches of any of the Colorbond range of colours. The samples are relatively true to colour and you can quite decisively use them to narrow the choice down. Check out the Colorbond range of colours on our website (scroll down to "colours" and click on them) http://www.asapgaragedoors.com.au/garage-doors. Consider Ironstone as a first choice which looks like the blended colour of the driveway, or Woodlands Grey, Basalt, Jasper or even Monument. Keep in mind that lighter colours will stand out more against the brickwork while darker colours will recede and the doors will not dominate the look of the house. The white-backed curtains are a good example of how colour can be a distraction. On first glance at the photo, the curtains stand out. I would change the back of the curtains to a darker colour. If you can't find a Colorbond colour that suits, you can elect to have the doors powdercoated in any Dulux colour.

I agree with your concern. We live in Wooloowin and have seen so many colonials lifted way too high, They have been ruined. I much prefer it when the old house is left low and extend out the back. I really love mixing new with the old. Space permitting, not sure that an extension would cost that much more than lifting when you factor in all the costs.

You say you want stain ideas for garage door. This seems unusual, because usually garage doors are not painted, they come in a colour made in a factory. Do you just mean colours. I would suggest Dulux beige royal for render. Colorbond Evening haze for garage door. Then a cedar stain for front door. Or the front door could be any colour really. Maybe Evening haze to match garage door, or even a red front door.