1) FAA702 is supposed not to target "US persons" at all. But FAA703 and 704 are intended to target US persons outside the United States. They are more restrictive, and surely less often used, but they're still there.
2) Have you actually read the ruling http://www.fas.org/irp/agency/doj/fisa/fiscr082208.pdf in the Yahoo! FISA case which was http://www.nytimes.com/2013/06/14/technology/secret-court-ru... recently reported? It's all about 703-like surveillance on US persons. And it contains this:
"2 . The Foreign Intelligence Exception . The recurrent theme permeating the petitioner's arguments is the notion that there is no foreign intelligence exception to the Fourth Amendment's Warrant Clause. 6 The FISC rejected this notion, positing that our decision in In re Sealed Case confirmed the existence of a foreign intelligence exception to the warrant requirement. "
You may want to read that again. IANAL, but as best as I can understand this is the FISC appeals court (the secret intelligence court's appeals court) affirming its belief that while law - the FISA - prevents (some) no-warrant searches for "foreign intelligence information" on US persons, this is not actually necessary to comply with the US constitution, because the Constitution does not prevent such searches at all. As soon as a foreign intelligence justification exists, open Sesame! the Warrant Clause goes away and the US government can search US citizens without any warrant. It is (according to this theory) only out of the goodness of Congress' heart that this isn't permitted already.