New to Java

I know what the acronyms stand for. I've done several internet searches and read several posts that give vague answers but I still have many questions:

Does J2EE use J2SE. Are certain APIs J2EE only?

I'm trying to get some sample code to compile and I get an error:
"package javax.servlet.http does not exist"

Is that a J2EE only API? How do I know which APIs are J2EE? Can I do servlet or JSP or Struts development with J2SE (was hoping to use the new Tiger features)?

Do I use J2EE with an already installed version of J2SE (such as the new 1.5) or is J2EE a superset of J2SE functionality and completely separate?

I read somewhere that the difference between J2SE and J2EE was a licensing difference only and not a technical one. Something like you have to pay Sun to have your product J2EE approved but technically they are equivalent. Is this accurate?