You do not have to have “Toon World” on the field to Summon or Set “Toon Gemini Elf”, or to attack with it.
The Summon of “Toon Gemini Elf” is a Normal Summon, not a Special Summon (even if you have “Toon World” on the field). So you can Normal Summon it in face-up Attack Position, or Set it in face-down Defense Position.
You don’t pay Life Points to attack with “Toon Gemini Elf”. If your opponent has a Toon Monster on the field, “Toon Gemini Elf” does not have to attack it. However, it will prevent “Toon Gemini Elf” from being able to attack directly.
“Toon Gemini Elf” can attack directly, but only while “Toon World” is on your side of the field. (Unlike previous Toon Monsters, which can attack directly even without “Toon World”.)