I thought the source of some of this data was Snowden's access at his own discretion, with his own keys and others' that he obtained?

I say "some" since Schneier has stated he now considers there to be at least 3 leakers... https://www.schneier.com/blog/archives/2014/08/the_us_intell...

The other two leakers got their information from somewhere, and it could have also included access at their own discretion.

One can hope. When Binney blew the whistle on the NSA he specifically said that he saw a request for Senator Obama's communications during his time there, as well as other elected officials.

> Although I'm not familiar with the _actual_ operating procedures involved

Their official line is that the data isn't being collected, correct?