How co-planar and co-rotatory are the Milky Way and its constituents?
As far as we know exoplanetary systems have orbital planes that are randomly distributed with respect to the Galactic plane. Indeed our own ecliptic plane is quite inclined with respect to the Galactic plane - as one can readily tell from the fact that the planets are not always seen against a background of the Milky Way.
Further details and some references can be found in answers to the related questions Detection of exo-planets and Do the axes of rotation of most stars in the Milky Way align reasonably closely with the axis of galactic rotation?