Hey, I just finished prototyping something a little similar to what you’re describing (Not including static forces like you’re describing, but just using basic inputs. As its first person there’s no camera controls, but you could probably use something similar in defining vectors or such. It pretty well does what was described by James above me, minus the modifying factors (Add in a vector * float multiplication for the speed + multiply it by delta time if need be). The input axis should be easily editable in Edit>Project Settings>Input. As for Gravity, that can be toggled/set easily, just right click and search for ‘gravity’. 
https://dl.dropboxusercontent.com/u/17693891/Temp_Example.png