I went through that last year. And, whatever you end up using, the Ikea kitchen planner is a great help in working through choices, layout etc. I can recommend IKEA cupboards, which I got in two colours (antique white and a light ash) - and their installation is even cheaper if you put the cupboards together yourself (even doing the frames for a carpenter is well worth it). The drawers and drawers inside drawers are excellent. I also had to use Kaboodle from Bunnings, as I wanted a corner pantry - it's a system that's also worth considering - my pantry is well made and goes well with the other cupboards. I didn't use IKea for benchtops and splashbacks, as my carpenter had a supplier from whom he could stuff wholesale, which cut costs as well. Twelve months on, I'm still very happy with the kitchen, the quality of cupboards etc.

I have used the following company for kitchen upgrades. If the layout and carcasses of cabinets are good, then this would be a good solution. I'm sure there are other companies that do the same. https://granitetransformations.com.au

It's an open book really. Since you are changing the gutterings and the windows are plain aluminium you can choose any colour your please. It'd personally go with a classic neutral tone, not white, which can look very dated very quickly and shows up every bit of dirt splashed on the side of the house and blown in on dust.

Maybe a cream or stone based white colour if the awnings are going to stay? This would also match the roof and could be ok with the gutters if you don’t want to change them.