I didn't know people didn't know he was really doing that stuff. I could've swore I saw something (maybe on Cracked?) months ago about the plane stunt specifically, and there was tons of press about climbing the building.
Personally I think the Mission Impossible movies are pretty meh. There's impressive parts to them (usually Cruise's stunts) but the rest is often mediocre. First one was ok, the second one just got too silly, 3 was fairly enjoyable (I think it might be my favorite). The one with Jeremy Renner I thought was just plain bad like Michael Bay level of bad (other than the stunts), and so I kinda don't really care any more (isn't Renner supposed to take over?). But then the odd number ones I think have been much better than the even ones.
I'm with KT here. The bricks I would be shitting would prevent me from making it up the ladder.
And then to take your hands/legs off all physical support and smile at the camera? FTS.
I'd guess it is very likely that the makeup of his brain means he just plain does not get the feelings that a lot of people would in the same situation. It's less balls and more just that he doesn't have to deal with the same level of stress/fear so he can focus on the physical part. Likewise, with all of the stuff he's done he's actually prepared himself (and his body) for that stress. That's not to say it isn't impressive, but there's reasons why it isn't quite as crazy as it seems.