Can anyone tell me why there are apparently particles around the edge of my collision geometry that are merging with the mesh of the fluids?

Also how do I smooth the geometry but still keep the sharp edges without changing the over shape/silhouette for rendering? (I've used the smooth node but it smooths too much and loses its shape).

I think your sim is too low resolution…
to smooth it theres a filtering parameter in the particlefluidsurface node but to get good result the
sim res must be high enough…