Sorry for the issues.
I use ENTER to add a little sense of tension with having to take your hand off the mouse temporarily. Since I make shooters, I like using it because it amkes the player temporarily defenseless.
F1 and F2 were just oversights. I assigned them and left them as is to work on other stuff in the game.
The keypad should've worked without the NUMPAD. I am not sure why it wasn't working for you.