A few changes have happened: explosion in number of systems, decline in quality of NSA staff (due to better opportunities elsewhere) on the tech/IT side, increase in contractors (who also tend to suck), politicization (since in the 1990s there was no clear mission, and in the 2000s there was not as morally justifiable a mission).
The NSA IT people I've met in the 2000s would not be people I'd hire to do IT/security. The older "former NSA" people I know are people I would gladly work with.
2) It appears Snowden has somewhat overrepresented the level of access he had.