You list the following:
Bonnet, grilles, bumper, lights/indicators and fenders
Then want to know about the cradle. Not sure what you mean by that.
But when I did it, it was the following:
1. Bonnet + kidneys
2. Fenders + side indicators. Important, you need to increase the length of the side indicator cables, otherwise they will be too short...I learned the hard way.
3. Lights + dont forget the bottom bracket is different for pre-FL to FL
Also the strips below the lights are different. Not too mention, if you have washers, the bit that pops out is different but the pump is the same.
4. Bumper. Now I had a Mtech1 bumper, so it stayed the same. But you will need different brackets on the sides for the bumper to fenders. Its just the normal FL brackets. Also different fog lights from pre-FL to FL.
Cradle, I guess you mean the crash bar? As far as I know, they the same, you just need to mount the new bumper to this before putting the crash bar back.
I think the easiest is if you have a donor vehicle, but its possible to order all the parts from BMW at a huge cost. I had money from the insurance which helped a lot in my case.