hey hey boyelektrik!

i hope i can help....
here we go. first of all caste is the polluted form of varnasrama dharma- which is a system that includes 4 types of individuals- who perform various activites and services that maintain society and help it function in a pure and god centred way. now, what is verrrrrrry important to understand is, is that regardless of birth, depending on ones natural propensities, he/she can flourish in many different ways. for example, although i was born into a family that is without a varna, i perform the functions of a brahmana (although in kali yuga there are no real brahmanas- only those to keep the worship of deities going) because this is my propensity. it is open to all. krsna is available to all.

arjuna had to fulfill his duty as a kshatriya (warrior). now, we must understand that this is not to just condone mindless killing, but to uphold what is pure an good. he had to rise above temporary attachments (family friends etc) and accomplish his duty. now, he was not forced to do this. krsna gave him this information, explained why and then says "yah kuru tathachasi" this is the information do with it what u will. ultimately the decision was his. he understood that because the soul is eternal there is no reason to fear death. and that the highest order is to surrender to krsna (god incarnate). and anything performed in the service of krsna is without reaction.

now as for the planets etc, there are many different levels of "heaven" if u will. the highest abode is of course goloka vrndavana (krsnas abode) and then there are the lower planetary syetems. we go to the place that we will have worked for in this life. it is up to us. if we desire sincerely to go back to krsna then he will fulfill that desire, if, on the other hand we desire things away from krsna then we shall get that.

i hope this helps, if not please ask away....
much love
hare krsna
manu dasa

One interesting translation is "The Bhagavad Gita : A Walkthrough for Westerners by Jack Hawley". I believe it is out of print now but not difficult to find on Amazon. When attempting to explain why I so deeply connected with the Gita to my mother, raised in a secular/lightly christian environment, I handed her this book. Jack succeeds in relating many of the concepts- most particularly those of duty in the passages you speak of- in a way that is very relateable to life as most people in the 'west' know it. Highly recommended.

Bhaktisiddhanta in his commentary of the Caitanya Bhagavata gives numerous quotes and evidence from Mahabharata and other scripture that caste is detrimined by ones guna - nature and ones karma- activites and is has nothing do to with birth whatsoever this is explained by Krishna in the Gita in the fourth chapter Bhagavad-gītā As It Is 4.13

cātur-varṇyaḿ mayā sṛṣṭaḿ

guṇa-karma-vibhāgaśaḥ

tasya kartāram api māḿ

viddhy akartāram avyayam

SYNONYMS

cātuḥ-varṇyam — the four divisions of human society; mayā — by Me; sṛṣṭam — created; guṇa — of quality; karma — and work; vibhāgaśaḥ — in terms of division; tasya — of that; kartāram — the father; api — although; mām — Me; viddhi — you may know; akartāram — as the nondoer; avyayam — unchangeable.

TRANSLATION

According to the three modes of material nature and the work associated with them, the four divisions of human society are created by Me. And although I am the creator of this system, you should know that I am yet the nondoer, being unchangeable.
www.bhagavadgitaasitis.com/4/13/en

please note that there is no mention of Janma - birth this is eloborated in Mahabharata how one is considered to be of a particular varna based on their actions and nature.



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Arjuna was fighting a just cause and the supreme LOrd was there to confirms this, Our war are so material motivated that you cannot really find a circumstance wherein there could be such a just fight. For example Krishna most recent incarnation according to the Vedas is Sri Caitanya Mahaprabhu the Kali yuga avatar. He did not seee fit to endorse any of the fighting that took place during His time rather He introduced nonviolent civil disobeidience

"The Muslim magistrate of Navadvīpa took up the complaints of the brāhmaṇas seriously, and at first he warned the followers of Nimāi Paṇḍita not to chant loudly the name of Hari. But Lord Caitanya asked His followers to disobey the orders of the Kazi, and they went on with their sańkīrtana (chanting) party as usual. The magistrate then sent constables who interrupted a sańkīrtana and broke some of the mṛdańgas (drums). When Nimāi Paṇḍita heard of this incident He organized a party for civil disobedience. He is the pioneer of the civil disobedience movement in India for the right cause. He organized a procession of one hundred thousand men with thousands of mṛdańgas and karatālas (hand cymbals), and this procession passed over the roads of Navadvīpa in defiance of the Kazi who had issued the order. Finally the procession reached the house of the Kazi, who went upstairs out of fear of the masses. The great crowds assembled at the Kazi's house displayed a violent temper, but the Lord asked them to be peaceful. At this time the Kazi came down and tried to pacify the Lord by addressing Him as his nephew. He pointed out that Nīlāmbara Cakravartī referred to him as an uncle, and consequently, Śrīmatī Śacīdevī, the mother of Nimāi Paṇḍita, was his sister. He asked the Lord whether his sister's son could be angry at His maternal uncle, and the Lord replied that since the Kazi was His maternal uncle he should receive his nephew well at his home. In this way the issue was mitigated, and the two learned scholars began a long discussion on the Koran and Hindu śāstras. The Lord raised the question of cow-killing, and the Kazi properly answered Him by referring to the Koran. In turn the Kazi also questioned the Lord about cow sacrifice in the Vedas, and the Lord replied that such sacrifice as mentioned in the Vedas is not actually cow-killing. In that sacrifice an old bull or cow was sacrificed for the sake of receiving a fresh younger life by the power of Vedic mantras. But in the Kali-yuga such cow sacrifices are forbidden because there are no qualified brāhmaṇas capable of conducting such a sacrifice. In fact, in Kali-yuga all yajñas (sacrifices) are forbidden because they are useless attempts by foolish men. In Kali-yuga only the sańkīrtana yajña is recommended for all practical purposes. Speaking in this way, the Lord finally convinced the Kazi, who became the Lord's follower. The Kazi thenceforth declared that no one should hinder the sańkīrtana movement which was started by the Lord, and the Kazi left this order in his will for the sake of progeny. The Kazi's tomb still exists in the area of Navadvīpa, and Hindu pilgrims go there to show their respects. The Kazi's descendants are residents, and they never objected to sańkīrtana, even during the Hindu-Muslim riot days."Śrīmad Bhāgavatam, Introduction



The planets are physical and subtle destinations, for instance you could possible go to such a planet but not experience any life there being taht is is one a different plane.