I'm not sure about your second wonder, but as to the first...
I guess for Tiger (and any player, really) it's totally a mater of pleying one's own percentages. If Tiger has, say, 265 yards into the hole and he decides to go for it, it must be because Tiger determines simply that he is more likely to get it in the hole in three from 265 by hitting a fairway wood than to get it up and down from 60, 80, 100 yards; whatever his layup yardage would be. Yes he's got a great short game, but he's good enough to have some kind of expectation to put it in easy up-and-down range, even with the pond by the green.