The most basic setup would look like this:
However, what you really need is a solid 6DoF, handling gimbal locks.
In order to get this working properly, you’d need to set up proper movement first. And only then worry about adding mouse screen input speed.
If you’re new to all this, may I suggest you start with a [6Dof][2] tutorial:
Link to the tutorial is in the very first post. Once you have it working, what I said above should make more sense.