[Advaita-l] What is Samadhi?

[Kuntimaddi Sadananda]

PraNAms to all.
There is lot of confusion in the Facebook discussion groups - many coming from Ramana Maharshi groups -1. Samadhi is required for Self-Realization and 2) the mind needs to be eliminated to attain Samadhi for self-realization (mana vinasha). Many quote from the books that have question-answers sessions Ramana Maharshi had with disciples. There are also many disciples of Ramana Maharshi who further endorse the above statements. There are also JK groups that denounce all methods as they all condition the mind. 
Some even quote Vivekachudamani sloka 447 or something that says the mind is a problem and one has to have a thoughtless mind for self-realization. 
1. What do you think is samadhi? 2. Is a thoughtless mind required for self-realization?3. What do you think is involved in self-realization?4. Is akhandaakaara vrutti involves thoughtless state? 
I am posing these to get input from all the scholars here. 
Hari Om!Sadananda