Federal law trumps state law in all cases of interstate commerce including international commerce.
Not in the Case of Colorado & Washington and their overturning Federal marijuana prohibition last year... if the Fed won't back down this will become new caselaw when the supreme court gets around to listening to it. The Fed argues they have jurisdiction over marijuana because of interstate commerce. This is the law of the land from Ashcroft Vs. Raich.
The rules for an individual business to do it are in place at the federal level.
I disagree sir, else you would see people doing it. We are all awaiting the SEC to make it's rules. There are other types of funding like SCOR which is done within the boundaries of a state but you cannot crowd fund in the USA yet because the SEC won't let you.
"Unlike some of the other provisions of the JOBS Act, before crowdfunding is lawful the SEC must proposed and finalize additional rules. Despite a December 31, 2012 deadline, no rules have been proposed."
http://www.forbes.com/sites/deborahljacobs/2013/04/17/the-trouble-with-crowdfunding/