In theory it sounds nice, but how many black ops and secret budgets already exist? "Defunding the NSA", will just mean its "official" budget will be cut, and under everyone's noses, they will keep being funded through secret budgets.
I'm not saying it shouldn't happen - eventually - but first the priority should be to repeal the Patriot Act and the FISA Amendments Act, and end the secret FISA Court, or at least overhaul it in such a way that it's public, judges get elected in a much more democratic way than simply having one person naming them, as it is right now, and allow adversarial hearings, and for people to be able to use FOIA against this sort of spying.
If it's done on an American citizen (under a proper warrant - and not en masse), then that citizen should be able to request a FOIA for it, and get an almost completely unredacted document. If there's an investigation done on him currently, then at most he can get a few months delay, to a year. After that everyone should be able to use FOIA to get these documents.