No, it's not necessary to create a Surface or a Spline to create the FP object.
For this purpose we added a new option the the create panel: Icon Mode (as other similar plugins). It lets you to create an empty FP object (just the icon), and define the distribution mode and geometry later.
Regarding Redshift, you must report the problem to them.
With this renderer, we just expose an interface to get the Forest items, but the rendering process is implemented by them. This workflow is common to all GPU renderers.