Hinduism is very vast and it contains various schools of thought. So there can be different tenets from different schools of thought. Having said that let me answer the various aspects briefly as per your question:
There are no common rules of morality. Depending upon the time and situation it can vary from person to person. One thing can be moral at sometime but immoral at other. So what is moral and what is immoral for a person depending upon his caste (varna), order (ashrama) and time and has been detailed in many scriptures like the Manu Smriti and the puranas. So the Gita says the scriptures are the authority regarding what should be done and what shouldn't be done:
One should therefore understand what is duty and what is not duty by the regulations of the scriptures. Knowing such rules and regulations, one should act so that he may gradually be elevated. [BG - 16.24]
Ethics are simple and well known. For example: tell the truth, vasudhaiva kutumbakam (whole world is but one family), treat father, mother, guests as god and so on.
satyaṃ vada | dharmaṃ cara | svādhyāyānmā pramadaḥ |mātṛdevo bhava | pitṛdevo bhava | ācāryadevo bhava | atithidevo bhava | [Tait. Up. - 1.11]
-Tell the truth, follow dharma, do not neglect in daily study of scriptures, treat mother as a god, treat father as a god, treat teacher as a god, treat the guest as a god.
The existence is composed of insentient parts consisting of material elements like earth, water, fire, air, etc. and sentient part comprising of jivas or souls. Insentient part (jada) is called apara prakruti and chetana jiva is called para prakruti:
Earth, water, ﬁre, air, ether, mind, intelligence and false ego – all together these eight constitute My separated material energies.Besides these, O mighty-armed Arjuna, there is another, superior energy of Mine, which comprises the living entities who are exploiting the resources of this material, inferior nature. [BG - 7.4,5]
Regarding planes of existence it is a commonly known belief that apart from earth there are also heaven and hellish realms.
4.Origin of Life
Everything originated from God. It was only God that was existent in the beginning. He desired to create the beings and did austerity and from that everything here was produced:
ātmā vā idameka evāgra āsīt sa īkṣata lokānnu sṛjā iti [Ait. Up. - 1.1.1]
- Only the Self (Brahman) was in the beginning. He desired to create the beings.
sa tapo 'tapyata sa tapastaptvā idaṃ sarvamasṛjata [Tait. Up. - 2.6]
- He then got heated in heavy heat (i.e. in the heat of austerity). After getting heated by austerity he created all these.
5.Purpose of Life
To develop detachment towards this materialistic mode of existence and grow attachment towards God:
śāstreṣv iyān eva suniścito nṛṇāṁ kṣemasya sadhryag-vimṛśeṣu hetuḥ
asaṅga ātma-vyatirikta ātmani dṛḍhā ratir brahmaṇi nirguṇe ca yā [SB 4.22.21]
It has been conclusively decided in the scriptures, after due consideration, that the ultimate goal for the welfare of the humans is detachment from the bodily concept of life and increased and steadfast attachment for the Supreme Lord, who is transcendental, beyond the modes of material nature.
From a social point of view, Hinduism accepts the four purusarthas viz. dharma, artha, kama and moksha as the purpose of human life.
Only 3 paths (karma, bhakti, jnana) exist for attaining the end result of liberation. Whatever other path we know goes under either of these three:
yogās trayo mayā proktā nṝṇāṁ śreyo-vidhitsayā
jñānaṁ karma ca bhaktiś ca nopāyo ’nyo ’sti kutracit [SB - 11.20.6]
The Supreme Personality of Godhead said: My dear Uddhava, because I desire that human beings may achieve perfection, I have presented three paths of advancement — the path of knowledge, the path of work and the path of devotion. Besides these three there is absolutely no other means of elevation.