Hi there, I have done some basic python scripts before for gimp. Providing that there's no rush on delivery I can make this one for you.
Only question I have is what's the difference between step 5 and 4? I mean in step 4 you already explain the input image will be loaded in the center of the LAYER2 of 500x500, so what's exactly step5? Give me a shout if you're interested.
Cheers!