Freud, the originator of the concepts that grew into our notion of the 'subconscious', would surely disagree with your first point. He was attempting a form of biological reductionism when he proposed the psychoanalytic theory. All of his reasoning about primary process thinking and remnants of the developmental process is meant to reduce human motivation to biology and history.
The theorization of the primary process does not increase the perceived complexity of thought, or render it more holistic and independent of biology. Instead it reduces the apparent complexity by presuming that emotional and logical resolution happens in passes, much like Chomsky's notion of deep-structure and transformation makes language more easily modeled mechanically, rather than less so, by theorizing layers of processing that can be detached from one another and separately analyzed.
In fact, the idea that a good part of your everyday motivation is not conscious to you ties the mind to the body more strongly. It leaves decision-making activity in the brain that may or may not be in the mind as it is imagined by idealists. If an obsession is something like a seizure, then interest and focus are biological things, not esoteric qualities of mind.
And even if subconscious content is taken to pump up the volume of what is mind, the few well-articulated forms (starting from the various forms of psychoanalysis, but also including cognitive-behaviorism and other models) all do so by presuming a separate layer of mind that we share with animals or a layer of the mind that is shared between humans. Few absolute mind/body dualists want the idea of mind distributed around the biological tree or attributed to groups and cultures. It makes for a muddy wake of confusing issues around what kind of things do and do not think. This does not help arguments that start from looking inward, as most dualist philosophies have. If 'mind' is not primarily a human aspect, it would make just as much sense to look into the behavior of a dog, or of an army, as of a man. It would give the process some objectivity and perspective.
So, while I am personally convinced of the role of the subconscious, and there are whole journals are devoted to psychoanalytical research, with a major component of their content devoted to grounding the theory in fact, I see it as a theoretical step away from, rather than toward mind/body dualism.