it depends on what Pokemon you put in the day care or what trainer you get it from like the egg you get at iron island is a riolu. and the one you get from the elite for person is a togepi
Use POKESAV to get an egg, and hatch it in Platinum
yes
It Takes 5100 Steps to Hatch Staryu EGG
Yes. Apparently it is easier to hatch shiny Pokemon from an egg in Platinum if it's parents are from another country.
Don't hatch it unless you want your game deleted.
There is absolutely no way to hatch it.
In PokeMon Platinum The Answer is 5301
Carry the egg in your party for approx. 6,400 steps
If you are talking about the bad egg, it does not. That's why it is called a bad egg.
a random Pokemon will hatch
You can't "find" him. You have to trade the egg from Pokemon ranger over to platinum, where you can hatch it.
That's hard as you can never be sure.