As for the latter, I'd be very surprised if what affected the sell colour was the same thing that affected the feather colour. Not that I know, but is sounds unlikely.
Budgies, and most other birds that breed in an enclosed nest, lay white eggs - they don't need the camouflage. It really has nothing to do with the feather colour. Open nest breeders lay a variety of coloured/speckled eggs, usually to match the background of the nest.
I have pots of seeds growing all the time. As they nibble away at one lot the others grow. The birds (cockatiels) love them and they are really good for them.t