Re: Freedom is slavery ..
"The NSA has been hoovering up the worlds communications for decades." Of course they have - the NSA since 1952 (65 years) and its various predecessors from 1917, for a total of a full century and counting. It is their mission. The implicit suggestion that the US or NSA are unique in this is absurd, as quite a few countries (including the other four of the Five Eyes) are active in the same sort of activity, for the same reasons.
A significant part of this "hoovering" is, for technical reasons, conducted within the US, and wherever done will collect information pertinent to both senders and receivers, even when only one of them can plausibly be thought "foreign." That probably is how Ambassador Kislyak's conversations with Michael Flynn were collected. It may be unfortunate, but plainly is unavoidable, that some "US Person" communications will be collected. Much has been made of this type of collection, but it is permitted by the operative laws, which the Congress may, if it wishes, adjust as it sees proper.
Most of the collected communications, especially in later years after exponential growth of Internet communication volume, has almost surely been discarded, a large part of it because of legal retention limits, but mostly because automated filters reject it or administrative retention limits based on practical considerations are reached.
It is incorrect in part to say the legal provisions were secret until Snowden leaked them, however. They are, and were, generally available in the US Code (Title 50) and were the subject of extensive and well publicized hearings around 1976, and legislation in 1978. The Foreign Intelligence Surveillance Act was amended in 2008 after additional hearings. Executive order 12333, with various amendments, has been in effect, and available in the Federal Register since December, 1981. The Foreign Intelligence Surveillance Court and the FISC Court of Review also were established in the law; they were no secret, either, despite the fact that they deal with classified material and issue classified decisions. Those classified decisions, along with the classified briefs and arguments that preceded them, comprise a major part of what was kept secret until (and mostly after) Snowden leaked them.
James Bamford's books, as well as others, along with numerous reports in major news publications like the New York Times and Washington Post revealed a good deal about NSA activities over its lifetime, so many, maybe most, NSA surveillance activities were not secret, although most people were, and probably still are, ignorant of them.
Did the NSA sometimes exceed its authority? Certainly, and in some instances they were taken to task by the FISC and required to step back. In other cases the activities got congressional blessing after the fact (e. t., the US Patriot Act). In quite a few cases, the excesses were technical errors or, in a few, employee misconduct. Based on reading a significant number of the documents Snowden leaked, in addition to or instead of the breathless reporting about the documents does, in fact, suggest rather strongly that NSA management has established meaningful and generally effective controls and auditing procedures over authorized activities; that the NSA staff have implemented many of them in software; and that the analysts and other staff generally adhere to them.