We made the eggs in home-ec when I was in jr high, so not so difficult. You just need a steady hand, and an awareness that you will probably break a few. Essentially, you just lightly wet some sugar with a few drops of water/color and then pack into a stiff mold, and allow it to dry. Components get attached with royal icing.
That's quite the display, I can see why you're starting now.
You can always make all sorts of things in marzipan (better for fine detail), pastillage, or fondant. You should run tests or make your own marzipan, though. I made the mistake once of taking some lovely canned marzipan in a #10 can to a competition only to discover that it would not harden.