And is causal body + subtle body, same as subconscious mind?
There is no concept of sub-conscious mind in shastra since mind is not conscious. Mind appears to be conscious due to the presence of the Atman.
Mind is made of subtle substance that also makes up the subtle body.
The real sense-organs (indriyas) are their subtle counterparts that belong to he subtle body, of which mind (antahkarana) is the main component factor. They are composed of the same type of subtle substance as mind is, and can expand and contract as freely as mind.
Methods of Knowledge according to Advaita Vedanta, Perception, p 44-45 by Swami Satprakasananda
In any external perception four distinct factors are involved; the object, the cognate sense-organ, the mind (antahkarana), and the knowing self. In the absence of any of these no perceptions is possible. Of these four the self alone is intrinsically luminous; the rest are devoid of consciousness.
Methods of Knowledge according to Advaita Vedanta, Perception, p 46 by Swami Satprakasananda
The causal body or the karana sarira is so called because it contains the record of our karma which causes rebirth. It has nothing to do with the mind.