If you provide an ICO service to an American citizen, you may face a problem with American law, so it's not a wise decision, friend.
Indeed. But not if it's made totally legal. For example: mask it as something else but have the same principle as an ICO in the end.
It depends on your marketing team. An ICO can be established anywhere and can target any specific market. Try to make an idea that the US citizen would be interested in that way you can make an ICO for a specific target.
That's not an issue. The issue is the law of participation in ICO's for U.S citizens.