Handling object actions

I have looked at the forums and resources, trying to figure out how to tackle my current problem. I would like to create a trigger within the game world so when a player collides with the trigger, and they press my action key, the game will perform an action. The actions that i would like to be able to perform are:

1) generate a random number and store it in a variable
2) move an object along a path
3) add an object to the inventory
4) hide and display objects
5) display a gui window on the client

please can someone help me figure out how to script the engine to do this.