I think that Snowden making himself a part of the story was a defensive tactic. If you expect your government to not play fair - and he clearly doesn't - then getting your side of the story out into the open as soon as possible is wise. Otherwise, you run the risk of the propaganda machine spinning up and destroying the issue by destroying the man behind it. Being in the public eye also afford him some measure of protection against covert retaliation.
It's worth noting that Snowden has far greater knowledge of the score than the public does; the Guardian has many unreleased documents whose contents Snowden is obviously aware of. The fact that he's talking about things not directly backed up by what his newspaper contact has chosen to yet publish doesn't necessarily mean that he's making it about him.
As stated, absolutely. He qualified it with a "personal email address". Saying "Oh yeah, I could read the president's personal email" is just playing up the impact of the program by throwing a high-value name behind the assertion. The information there is that they can read personal email; the president's personal email isn't more technologically protected than anyone else's given the same provider.
It's worth noting that Snowden has far greater knowledge of the score than the public does; the Guardian has many unreleased documents whose contents Snowden is obviously aware of. The fact that he's talking about things not directly backed up by what his newspaper contact has chosen to yet publish doesn't necessarily mean that he's making it about him.