1. The document discusses various types of onomastic variation including acronyms, aliases, anagrams, nicknames, pen names, and stage names. It provides many examples of famous people's real names and their better known names or aliases.
2. Common reasons for name variation included concealing or changing one's identity, moving to or away from formality or ethnicity, or adopting a memorable stage name.
3. Names are also sometimes changed for marketing purposes like brand names or to symbolize something like "Uncle Sam" representing the United States.