There’s strong indications that at least a few of those congressmen already knew that something was something was very wrong, but due to the classified nature of the NSA’s/government’s actions they couldn’t go public with this knowledge, and could at most hint at it and hope the public caught on and forced an investigation, something that never happened.

Due to the speech or debate clause, they could have indeed gone public. Instead, they (supposedly) dropped oblique hints and attempted to get others, like Clapper, to reveal information – others, by the way, who were not protected by the same clause. When these ploys didn’t succeed they basically did not escalate the issue further, at least as far as it looks from the outside.

By the way, this strategy (going to Congress and imploring them to use the Speech or Debate clause) is exactly what Ellsberg did, although he couldn’t find anyone in Congress that would work with him (unfortunate, in hindsight). It was only then that he went to the press.

As to why they didn’t take the out you mentioned and just had the documents recorded publicly, it’s probably due to only being allowed to see the documents, no notes, no copies, no other people with them, so it would be at most ‘their word against the NSA’s’, and all the NSA would have to do to shut them down would be to claim ‘state secrets/classified/national security’.

This is not a 29-year-old sysadmin we’re talking about, it’s the Congress of the United States. Please explain the specific mechanism by which the NSA could have “shut down” debate on the floor if somebody really, really wanted it to happen. Not just one that you imagine exists, let’s talk turkey here.

Let’s say you’re right, and members of Congress did not push the issue because they did not have sufficient access to source documents. When Snowden decided to go public, he could have solved Congress’ problem, by making those documents available – to the appropriate members of Congress.

Not quite sure on the rules here

Clearly.

the USG considers merely making the documents public, no matter what channel they are going through, to be aiding the enemy, so that would not have spared him from the charge

You are wrong, because in this scenario Snowden releases the information/documents, in confidence, to a sympathetic member of Congress, not to the public. Maybe he does so to a member of Congress that has appropriate clearance or a trusted staffer with one, maybe in a secure facility – just to make it more ‘kosher.’ Then, the member of Congress enters the information into the record. The member of Congress is the one who releases the information to the public, and he or she would be protected in doing so by the speech or debate clause.

he would have been right where they could grab him, so odds are if he had gone through official channels as you say, he’d have been taken away to a cell somewhere while they tortured him for information and/or just let him stew for a few years ala Manning

That is pure speculation.

First, had he done this, they would have had much less to charge him with, since he released the information only to members of the US Congress, who arguably have both access and need-to-know. What would the charges have been? Be specific here.

Second, even if he were charged, it would be harder for the executive branch to pull any shenanigans because it would look much more like they were attempting to intimidate the legislative branch.

Third, let’s say he didn’t trust his friends in Congress to be able to protect him. He could have arranged everything, then left the country in advance of the disclosure – by Congress, not a foreign reporter – just as he did.

Fourth, as noted above, if he were maximally paranoid, he could have left first and delivered the information to Congress over the phone, courier, the Internet, whatever.