I had a really smelly egg, was covered in something so I dipped it in 3% bleach. I'm sure it will be fine as egg shells are theoretically waterproof. Smells nice and fresh now - I would not have felt comfortable putting that in my incubator the way it smelt.
I like the little details you added and those fans you found are brilliant with their feet all ready to be just placed in there.
I'd never heard of using Hydrogen peroxide. Problem with HP is that it makes my spray bottles leak and I don't want to buy a new spray bottle every time. Can eggs be...