My theory of why Hulk can do these things has to do with his innate nature of his being. If we think of the logistics of what Hulk is, an image from Banner's mind...repressed emotion, his Id, Ego, Super-Ego, survival instinct, his internal self defense mechanism externalized, etc (all that have been stated in comics)... he seems to be a creature of mind over matter, mind over energy, mind over mind.
There was a reason why long die-hard Hulk fans like myself loved Greg Pak's work on Hulk, and it's because there are little nuances about the Hulk and his abilities's that he built on that we were aware of that most casual Hulk readers were and are not.
Hulk has manipulated energy and done weird stuff before. Some of the first issues of Hulk that I read was issue TIH #242 & 243 (excellent story and should be read to understand him better), in those issues Hulk did something that the narration itself stated in the clearest language was and should be impossible by any being. Hulk being angry as hell, trying to get at Tyrannus somehow was able to grab hold of an energy field that was intangible...as if it was tangible (words from the story). The machine was built to withstand the power of the gods, called the Eternal Flame, and in the strory Hulk later completely destroyed it.
Hulk has been able to channel energy blasts through himself at times and shoot them back at an opponent. Hulk can see ghosts or astral forms/projections where others can't and he can also sense magic. He's been shown to locate Doctor Strange's home when it's mystically cloaked. Hulk has breathed underwater and in outer space. Hulk's mind once took him to a place where there was a town of people that may not have been in the immediate dimension. He's always from day 1 had uncanny accuracy when throwing at targets. Hulk can do more than just smash.
There is a post on another board called the Hulk Respect Thread where you can see Hulk's more incredible feats and abilities.
