Barbi, while a spirit/ghost may not be a physically living being, it is considered by many to be alive (regardless of the lack of a body). The consideration of a ghost as a being which is somehow trapped here is not the total of considerations of what a ghost is. For many who have dealt with both ghosts (or what people call ghosts) and spirits, a spirit is a real being while a ghost is usually a form of thoughtform. Ghost is often used to differentiate between a spirit (which generally has/is a soul/spirit) and a being which was created due to circumstances occurring. Usually these circumstances involve bad feelings, murders, etc, which cause a house and/or object to pick up on the thing itself.
While most traditions do have a form of "angry spirit" or "hungry spirit" these are not things which are called unliving. They are considered beings which, for one reason or another, cannot move on to the proper form of judgement/afterlife that those traditions believe in. Perhaps a description of what a ghost is and an explanation included would do better for you in the future.
I am confused by your statement that we have no control over our subconscious self and/or mind. We can influence it, yes, and we can even change things within it. While it is not totally under our control, that does not mean that only the subconscious self is existent when we dream. If used in a lucid dreaming context, or when one naturally has control over their dreams, there is no harm. Nor is there any harm in it if the individual means a spirit when they say a ghost. I have been visited by dead people in my dreams before and they changed a normal dream into a lucid dream so I could experience being with them. I never came to any harm from these visits, nor were any of them angry.
Yes, it is possible to "pull" a living being into your dreams or to "go" into theirs. I have worked with guides, deities, and spirits in my dreams before, as well as I accidentally pulled a friend into a dream before. Dreams are more than simple cut and dry things, but sometimes they really are just projections of our lives and/or desires.
I would do a bit of looking into lucid dreaming, dream journaling, etc, and figure out just what you want to get out of your dreams Jboy.