This is quite fun!
I think "Shift" or "Spacebar" better keys than "Tab" for switching tanks if WASD is movement. I can't reach "Tab" that well while keeping my other fingers on WASD.
I'd like autofire while arrows are held down so I don't have to keep tapping. This is particularly important for diagonal shots because it's hard to tap 2 arrows simultaneously, but it's easier to hold them down.