What, like 'cat /home/dirnsa/undercover_agents.txt'?
As for the question of how did he get a slideshow? I don't know, but it's not difficult to imagine that an attachment on an email is easier to access than a wiretapping database.
His lack of education is relevant because when you have at least some understanding of the depth of complex systems, it becomes very hard to imagine that a self-taught person has enough knowledge to speak competently about multiple such systems.
EDIT: let me amend this last statement, since so many people seem to want to focus on an extreme interpretation of it. Yes, very brilliant people do sometimes have no papers or letters backing up their knowledge. I think you have to admit, if you've dealt with enough such people, that they are the exception -- the mean and floor of that population's technical capacity is lower than of the educated population, in my experience.
Now your argument has to be that Snowden was exceptional -- where is the evidence for that? His pay? Who honestly believes salary is highly correlated with ability?