No.When they were making Spongebob they thought his name could be spongeboy,but someone else already had the name.(I don't know who)So they just called him Spongebob,so his real name is Spongebob.
It's possible. In Patrick SmartPants, Patrick calls Sandy 의해 her real name "Sandra". In another scene, he says [for Spongebob]: "Robert, my dear, it's no use."