Ask a lawyer is for analysis, not legal advice you can rely on, and your question is not general but very specific and complex.
If you have no physical presence in the US, that you don't have to register as a foreign corporation in any of those states. As to #2, no. As to #3, way too complex for a public forum, but the standard is "effectively connected with a US trade or business."
Answered on Feb 19th, 2013 at 4:09 PM