I've played with FPV Freerider for a couple of weeks now and have adjusted the setting to fly pretty close to way my FPV quads are setup. All the flight controls are fairly realistic except for the YAW. Any plans on improving the YAW control function?

Glad to hear that you have got it dialed in pretty close to your own quads. In what way do you mean that the yaw could be more realistic? I might be able to make some adjustments if you can describe it in detail.

Applying yaw also produced a little opposite roll. That is, is you yaw left, the qaud rotates left but the quad also roll to the right.

It actually doesn't produce any roll (although it may feel like it). You can check it in LOS view, you will see that the quad only rotates around it's own axis and doesn't roll. The perceived roll effect comes from the quad being tilted forward in forward flight (and the uptilted camera adds to the effect).

You can check that and compare to your real quad, perhaps your quad doesn't lean as much forward.