Inconceivable Topics: Vishnu and Krishna

Q. I understand Lord Vishnu comes from Krishna who is the source of all sources, but in Hinduism this conception is not there. My question is why is that?

Q. What are the similarities and differences between Vishnu and Krishna.

Vishnu is a plenary expansion of Krishna or Lord Narayana for the purpose of material creation. He is the same as Krishna in the sense that all plenary expansions are equally powerful as Krishna. In that sense, all the expansions such as Narayana in Vaikuntha are called 'Vishnu tattva' as opposed to the jiva-tattva or the miniscule living entities.

Q. 1. Is Lord Brahma guaranteed to return to Goloka Vrindavana at the end of his lifetime? I said that I believe it is not a guarantee but probably likely given that whichever jiva occupies the post of Lord Brahma will have 50/64 of the transcendental qualities.

I have gone through several websites for 'DASAVATAR' (ten incarnations), and there is a confusion whether Lord Krishna is an avatar or Sri Hari (the original Supreme Lord) Himself Who came down on earth. At a few sites Krishna is shown as an avatar and Balarama also as an avatar of Ananta Sheshanaag (also Lakshmana); while on some others Balarama is presented as avatar and they treat Krishna as Sri Hari Himself, the original Avtari, not an avatar.

Q. Why are worshipers of Krishna called Vaishnava, why not Krishnavas? Does this not indicate that we are actually worshippers of Vishnu?

Q. My question is regarding the Maha Mantra - HARE KRISHNA, HARE KRISHNA, KRISHNA, KRISHNA, HARE, HARE; HARE RAM, HARE RAM, RAM, RAM, HARE, HARE. Lords Krishna and Rama had different personalities and characters; both of them were avatara (incarnation) of Lord Vishnu in two different Yugas. My question is why these two names are combined in the Maha Mantra? Could you please kindly explain about the Maha Mantra? How did it derive? What are the meanings, if any, behind the Mantra?