That's quite a plateful of unanswerable questions, Patrick! I'll take you up on a couple of your offerings here and let Orin and David sample the rest.
You are entirely correct that the primary controversy concerns communications in which one party is in the United States and another is abroad. The NSA might intercept such communications using either of two models. Caveat: This is oversimplifying dramatically—you're right that there are probably countless different models, or, as our soon-to-be-departed AG would put it, "programs."
First, the NSA might "target" its surveillance directly at the U.S. person's "facilities" and thereby pick up all or many of that person's communications, including (but not limited to) those with persons overseas. Back in the old days, this might have meant a wiretap on your phone, for example.
What does DNI McConnell have to say about such "targeting" of U.S. persons? Well, as you noted, he said that if one were to do it without a FISA court order, "[t]hat's not legal, it would be a breach of the Fourth Amendment. You can go to jail for that sort of thing." (My italics.)
To which I say: Eureka! Someone in the administration finally acknowledges that the so-called "Terrorist Surveillance Program" that the president authorized from October 2001 to January 2007—which by all accounts did involve such "targeting" of the international calls of U.S. persons—was illegal: You can go to jail for exactly that "sort" of thing. It's right there in the U.S. Code. (Not that there would or should be any such prosecutions for surveillance that had the blessing of the Office of Legal Counsel at the Department of Justice—but that's another story.) Many of us have been saying for years that this surveillance outside the FISA box was illegal (see letters linked here), but to no avail. It's heartening that McConnell apparently knows how to read statutes and the Constitution better than does, say, John Yoo.
But going forward, such "targeting" of U.S. persons is almost certainly not what all the fuss is about. Which brings us to the so-called "Marty Lederman question," which I suppose I ought to know how to ask, seeing as how it appears to be my legacy.
The question, in a nutshell, is based on this basic story of what the NSA might be doing:
Assume the NSA computers are able to broadly intercept virtually all calls and e-mails going into or out of the United States, not by "targeting" Americans as such, but instead by performing a vast sweep of all foreign communications traveling over fiber-optic cables or "tubes" or some such thing (the technology is not my forte, alas) somewhere in the United States. This is an interception, in other words, of virtually all international communications involving U.S. persons—but look, Ma, no "targeting"!
Now, of course, the actual humans up at Fort Meade—and there are a lot of them—can't possibly read and listen to all international calls and e-mails that are caught up in this vast dragnet. And so those trusty NSA computers are designed to cull out the subset of communications that are most likely to contain information of value to the U.S. government—any information of value; it need not have anything to do with terrorists or other national security threats. (This culling is likely done by identifying certain characteristics of the "meta-data," rather than of the contents themselves. Meta-data-mining, as it were.) And then the actual humans at the NSA start listening to, and reading, those culled communications, many of which will involve someone in the United States. And, after reading or listening to those U.S.-person messages, NSA could then share them with other law-enforcement agencies, or perhaps store them away, in dossiers on the "overheard" Americans. It could even use what it learns as the basis for a FISA court order that allows the agency to "target" your calls directly (both foreign and domestic), if it can demonstrate probable cause that you are an agent of a foreign power.
And—here's the crux of the problem—if I'm reading the new law correctly, the NSA can now do all of this, with respect to tens of thousands if not millions of Americans' international communications, without satisfying any standards at all to the satisfaction of any neutral party (that is to say, a judge) and without any meaningful court or congressional oversight. As long as they can credibly say (as they probably could) that the sweeps of international communications are "directed at" folks who are "reasonably believed" to be overseas, rather than at their U.S. correspondents, they're home free.
And so here's that question again (or rather two questions): Is this constitutional? And, if so, should Congress authorize the NSA to do this without any check or oversight at all?