Every time I venture to whole foods I notice the ostrich and emu eggs for sale. The one obvious difference is size. Do the eggs taste the same as chicken eggs? Are they any different nutritionally? Can they be hard-boiled?
i have a friend who has 8 ostriches, and he eats their eggs all the time. the taste is (apparently) different from a chicken's... richer somehow, but not different in a bad way. he has hard-boiled them, but as roux says, it takes a LONG time to do it. i think he boils them for an hour, but don't quote me on that one. his most regular method is to drill a hole in it, drain it into a big bowl, blend it, and then makes scrambled eggs a cup or so at a time. he has found that he can freeze the leftover egg for eating later. as roux also said, one ostrich egg is about 2 dozen or so chicken eggs, so be prepared!
In order: broadly, yes though slightly richer; I do not know, but one ostrich egg is equivalent to approximately thirty chicken eggs; yes but you need to do it for (obviously) much longer and at a lower temperature--think more like sous vide, less like hard boiling.
I have cooked and eaten an ostrich egg once before and it was a mildly unpleasant experience.
It definitely doesn't taste like a chicken egg - it has a denser texture (almost rubbery) and a stronger taste. Scrambling it and using it as part of a frittata in two very large 14 inch pans, I was still scratching my head as to what I should with the leftovers.
Also, unless you have ostriches I know they can be quite expensive. The emu eggs seem like they would be a bit easier to handle, but still I'm not sure I would have any reason to buy one except for curiosity.
I've never had Ostrich eggs but I've eaten many duck and goose eggs that my family raised when I was a child. Duck and Goose eggs are richer (large yolks) and slighly gamey in flavor - you may enjoy this or find it unpleasant depending on your tasts. I quite enjoyed them.
Our birds were "free range" (they wandered in our back yard) and ate a lot of grass and bugs in addition to hand shelled corn which gave a deep savory flavor to the egg that you do not get with "feed fed" chickens.
There is nothing quite like Goose Eggs scrambled with a bit of butter sauteed morels for a country gourmet breakfast though.