Samurai_of_DOOM there are already clear instructions on the game. See, when you get enough money you can buy them.
On the upgrades panel, first row, there are 4 images with the "hero" performing the trick. Let's get the "Up-N-Out" as starters:
It costs $900 and, once you bought it, you can execute this trick by following the instructions:
Up + Up + Up
That means you'll have to press the up arrow 3 times in a row.
The same goes for the other tricks.
To find the gun you'll need to fill up both sinks but when the alien get inside, throw the hair dryer on the sink that is right below the mirror. Then you'll find the gun, kill the alien and save the human.
 "Shopping Cart Hero 2"){kind=icon}
 "Take Something Literally"){kind=icon}
 "Fly Hard"){kind=icon}
 "Infectonator!"){kind=icon}
 "The Visitor"){kind=icon}
 "3D Logic"){kind=icon}
 "Now Boarding: Episode 1"){kind=icon}