As I said before, these are high level design questions really, you need to work out how you want it to work and then go from there.
How do you want the game to turn?
At a thought “A” and “D” could turn you on the spot by adding rotation, or even simply turning you around, or the mouse could be used to freely look around, the possibilities are only limited by your choices.
So work out exactly what you want, then ask the question how do you do that exact thing. It will break your tasks down to very manageable sizes, and you’ll be able to get much more focused answers from others as well, as you’ll have specific problems.