I have no idea if you can attach a Kakadu annex to your Fiamma awning, but if you can, have a good look at the side rooms before you lay down the cash. I thought the front "verandah" would be the bees knees but it slopes down from the awning, and me being fairly tall, it was way too low. In the centre, between the awning and the outer front side, it was shoulder height. Not much fun stooping the whole time you are cooking a barbie, and even just getting in and out of the annex.
If you do have a wardrobe, it's a piece of cake to fit the shelves yourself. Just a tip though, ours weren't "fixed" so when the wardrobe was laid down to pack when it was empty, the shelves would drop out of place. Never did get around to screwing them to the supports...
Good choice with the Fiamma and portable panels too.
Hope this might help. Enjoy your new camper!