Yes. However, the consciousness of the soul is in a very covered condition in such bodies.

The soul is our real self; it is all-spiritual and eternal. When the soul comes to the material world, he accepts a material body, which comprises of a gross body and a subtle body. Mind is part of the subtle body; it is a subtle sense, sometimes called the 6th sense, distinguishing it from the sense of sight, sound, touch, smell and taste. The soul is the seat of consciousness, whereas the mind simple receives impressions from the five senses, and then processes those impressions by way of thoughts, feelings, and volition. The mind also is the resting place of our conceptions of life.

According to Srimad Bhagavatam, 12.2.20-22, the normal course of Kali Yuga ends with Kalki Avatar annihilating the millions of souls who masquerade as kings; these souls receive sayujya liberation, or a state of sinlessness, but their devotion to the Supreme Lord still needs to be awakened. The remaining souls are uplifted by the Lord's presence, they become transcendentally purified, and they come at once to the platform of goodness. These souls assist in populating the planet with other elevated souls, thus playing their role in ushering in the Satya Yuga.

In Chapter Four of Canto 12, we find a detailed description of what happens and the end of the Kali Yugas that come at the end of Brahma's day (i.e. after 1,000 yuga cycles are completed), as well as the end of Brahma's life. The basic idea is that the souls are held in a dormant state, with no manifested activities or forms, and they remain in that condition until the next creation takes place.

Jivas are eternal, but in conditioned life, when the term of existence in one body is finished, they transmigrate to another body. Ciranjivas are those who have a special capacity to live for a very, very long period of time, over a span of several yugas in that very same form. However, at the end of the allotted time, they also have to quit their body. Both jives and ciranjivas are entitled to go back to the spiritual world if they become pure in their devotion to the Supreme Lord. Otherwise, they will have to rotate in the cycle of birth and death.

No, a demon does not by-pass karma by detachment. A person of demoniac nature has the tendency to misuse even the best philosophy. Kamsa's behavior is a typical example to illustrate that knowledge can be dangerous in the hands of demons. However, abuse of a principle does not discredit the value of that principle itself.

Arjuna was also asked to be detached in killing his grandfather and teacher, but to serve the higher cause of fulfilling the Lord's mission. Since God is Absolute and equally merciful towards everyone, whatever He does benefits everyone. Therefore He is beyond all morality and rules, and His killing results in the liberation of the other's soul. This is not the same as the justification that Kamsa gave. Unlike Kamsa, the true basis of morality for the rest of us is to abide by God's laws, and by following this principle we can do equal justice to all. We do have to cultivate detachment, not to use as an excuse for justifying our whims, but to detach ourselves from our independent notions, so that we can act as an instrument of the all-good Supreme Lord, absent the intervention of our self- centered likes and dislikes.

The soul remains in a dormant condition for some time.

Spirit soul is eternal, and thus has no real business in this temporary atmosphere. If he manifests a desire apart from his spiritual nature, he obtains a material body suitable to accommodate that his material desire. At the termination of the particular body which the soul has been awarded, the soul quits that body and takes on another, according to the consciousness at the time of death. This is called rebirth or transmigration of the soul, and it continues on until one is free from all material desires, at which time the spirit soul can return back to the eternal spiritual world.

If someone lost their hard-earned money, the person himself is not hurt by the incident, but because they are attached to the money and identify it as their property, they have to suffer the consequence of the loss. Similarly, the soul mistakenly identifies himself with the material body, and thus becomes attached and 'conditioned' by the desire to enjoy the facilities of material existence. Therefore, he is forced to take another body to enjoy or suffer the consequences of past actions.

The term nitya siddha means those great devotees who are eternally manifesting perfected existence in the spiritual world or although sometimes appearing in this world amongst us for some purpose of serving the Supreme Lord, are actually never contaminated by the material nature at any point of time. The term nitya baddha refers to those who have been conditioned since time immemorial within the material world.

These two terms do not conflict with the two alternative positions for the soul, mentioned in the first part of your question. The grammar of the initial definition of the soul as marginal, however, as found in your question, needs to be modified:

"The soul is called tatastha, or marginal, because although it is spiritual in nature, due to its tiny existence, it can be influenced by either the internal (spiritual) or the external (material) energy of the Lord."

There is actually no contradiction in these two definitions.

That God is the ultimate controller does not imply that God is responsible for all our actions. Every individual is responsible for his/her own actions. We make our own destiny based on our desires and past actions, but that happens under the direction and sanction of God. If one is born in atheistic family, it is a result awarded in accordance with their own desires and past misdeeds.

God's ultimate control does not exempt us from bearing the responsibility to act in accord with His will and according to the codes of theistic conduct.

However, although our natures are greatly molded by the environment as you have described, even in the most unfortunate of circumstances one still has one's freewill and one could take that very situation as an impetus to take shelter of God. A person coming from unfortunate circumstances from birth may be inspired by God Himself, from within his heart, assisting him to understand God. The classic example is that of Prahlada Maharaja who, although was born as the son of the most formidable demon, became an exalted devotee by the association of Srila Narada Muni.

Realization of our spiritual nature takes cultivation. Regular hearing of spiritual topics such as Bhagavad-gita and Srimad Bhagavatam, and regular chanting of the Holy Names of the Lord are two of the most potent activities that can spiritualize our consciousness. Further, by applying the principles of Srimad Bhagavatam as we perform our practical devotional service, cultivating tolerate towards the dualities of the material world in the course of execution of our services, and being fixed in a service mood toward Krishna and His devotees can bring profound realizations in our hearts, spiritually empowering us to remain undisturbed in any circumstance.

This question was answered in a previous issue also. We always have the freewill to 'misbehave', but if we cent-percent reinstate ourselves in pure devotion during this life and go back to the spiritual world, Krishna promises that He will extend His special protection to us, in such a way that we never have to come back again and experience life in this material world. This is His special, causeless mercy.

The soul is being carried on the machine (yantra) of prakrti, or material energy, like a chariot carries a passenger. The body is performing activities, or prakrti is the performer, not the soul.

The soul's activity or business is to desire. We can also 'endeavor'. See BG 18.14 the living entity is called the 'karta' (doer) in the Secondary sense of one who makes an endeavor (cestah). Action is actually being carried out by material nature: See BG 5.14.