Re: The True Tony Stark
This is a good point... I'd assumed a lot of the seriousness I'd been picking up from Tony in the comics (which I've only started to read since Avengers) was due to my happening to focus largely on the Civil War and post-CW-fallout story lines. A lot of the events in there, obviously, weigh very heavily on him.
Another aspect of his personality that I've noticed in several of the comics, and which has been largely downplayed in the films, is the whole "futurist" concept -- the idea that as a genius, Tony is constantly anticipating possible future scenarios and preparing backup plans for them. Hopefully we get to see a bit of that in IM3.
But ultimately, yeah, he is a genius-billionaire-playboy-philanthropist.