Sri Sadgurubhyoh Namah
Below are the answers to the questions you asked,
1) What is Advaita ?
Advaita means 'No Two'. It doesnt mean one. No different entities like God, World, Jiva. Shankara says 'Brahma satyam, Jagan Mithya, Jivo brahmaiva na aparaha' meaning consciousness is truth (unchanging entity) and world is the transient, illusory, changing entity. Individual self is the same as Brahman / Truth. The advaita teaching is encapsulated in Upanishad vakya 'Tat Tvam Asi' (that thou art). You are that. Jiva is deluded with body consciousness, and thinks that body is real and world is real. As a result, Jiva suffers. When Guru points out the true nature of the Jiva as Atma / Brahman, then Jiva recognises its true self and becomes free. Jiva is deluded because of ignorance (avidya). Thinking that I am limited, I am body, I am mind, I am intellect is the ignorance. Because of Gurus grace in the form of teaching that I am not the body, I am not the mind, I am not the intellect, I am pure consciousness, I am Shiva leads to freedom and liberation.
2) What is Maya ?
Something which is not real appears as real. This is Maya. The world is continuously changing, but it appears as unchanging and same and constant. The world appears as solid, whereas in reality it is a wave of energy. Due to the limitation of the indriyas, we see world consisting of various objects. Jiva has the desire to possess the objects which are like mirage in the desert. Maya is also the power of Ishwara, the lord of universe, who uses this power to create the world. Individual Jiva has avidya and Ishwara has Maya. The creation of Ishwara is because of maya and it is perfect. The creation of jiva is out of avidya and it is imperfect.
3) What is Jiva ?
Jiva is Brahman (consciousness) at the paramarthik level. Jiva is the body, mind, intellect at vyavaharik level. Consciousness identifying with a body is Jiva. The I-am-body thought is Jiva. Jiva is a discontinuous entity, even though it appears as continuous. Depending on the interaction, a role is assumed. Consciousness if it is aware that it is playing a role, stays as consciousness. If consciousness forgets that it is playing a role and identifies with the role, then Jiva bhava emerges. repeated identification with a role creates vasanas and samskaras and then the identification becomes reality over a period of time and consciousness forgets that it is consciousness and will be switching identities from one role to another role thus strengthening the ego. The real substratum i.e consciousness is forgotten and it vascillates between identities. This continuous switching of roles/identities creates an illusion of a solid being called Jiva. When mind is silenced, the thoughts related to identities is also gone and only the substratum reality remains. Hence we need to meditate to quieten the mind to experience the reality i.e consciousness.
4) What is Ishwara ?
Ishwara is the lord of the universe. It is a wave in Parabrahma, All jivas are different waves in the ocean called Parabrahma. Ishwara is a special wave with omniscience, omnipotence and all omni qualities. The world runs according to the laws created by Ishwara, namely the law of Karma. The essential inner nature of Ishwara is consciousness and it is same as the essential inner nature of all beings.
5) How do you get advaita realization ?
By Sravana, Manana, Nidhidhyasa. Sravana is listening to vedantic truths like 'tat tvam asi' from Guru, Manana is remembering, meditating and contemplating on those truths. Once the truth becomes ones very own nature, guarding the truth every moment is Nidhidhyasa.
6) What are 3 important characteristics of stithaprajna ?
Bhagavadgita chapter-2 shloka-56 mentions the qualities of sthithaprajna,
"Duhkheshu anudvigna manah, sukheshu vigata spruha,
Veetaraaga bhaya krodha sthitha dhirmuniruchyate"
One who is not depressed in sorrow, one who is not jumping in joy (equanimous in joy and sorrow), One who is without attachment to likes and dislikes, one who transcends fear and anger is established in Stitha prajna (balanced mind).
7) Explain what is deep sleep. Why it is important for self realization ?
Mind has three states. Waking, Dreaming, Deep sleep.
Waking state : I am there, world is there, outside of me. I cognise objects separate from me.
Dreaming : Aware of objects, but sense of I is weakend, though still there. I cognise objects inside my mind.
Deep sleep : Mind is dormant. Neither I am aware of objects, nor world nor sense of myself. It is a state of absence.
Understanding of the states of consciousness is very important for self realization. The three states of consciousness is taken as an example to explain the truth in Mandukya upanishad. The three states of consciousness is known as Avastha traya in sanskrit. By carefully observing the three states that mind undergoes, we will understands that there is a sakshi that is observing these states of mind. That means the continuous entity is the sakshi, and not the waking consciousness alone. The Witness is common to all states. This is turiya sthithi.