I'm sure the old gamepad hands know about these, but anyway.
JoyToKey. Assign keystrokes, mouse buttons, mouse wheel movement, and mouse movement to gamepad buttons and axes. Turbo. Simple GUI interface. Multiple profiles.
AutoHotKey. Everything above, and more. (Toggle keys, and mouse buttons on and off for example.) Much more power, much more work.
Joypad inputs will get to the game as well as the emulated input (if the game is looking for it). With key presses it doesn't matter, the key press is registered along with the joypad input. The mouse cursor is centered on Naija when the game receives joy input however.
Possibilities: Assign songs to the POV hat (D-Pad); Use the sticks to zoom and move the map; "Look" with the joypad (this is limited to about half the distance that the mouse gives, but you can swim and have it automatically look in the direction you're swimming); Save your finger sanity with turbo fire; Have the mouse swimming physics (momentum after input ceases) while using the joypad. There are some side effects to some of these (mouse cursor showing).