How does Judaism view Near Death experiences? do we believe they are a figment of the imagination, or do we accept them? and if we do accept them, how do we believe stories of people who claim that Yushka came to them?
There are a number of places where near death experience are described in the Talmud.
Here are 2, but there are more similar cases:
מסכת בבא בתרא דף י' א
Joseph the son of R. Joshua. He had been ill and fell in a trance. [After he recovered], his father said to him: ‘What vision did you have?’ He replied, ‘I saw a world upside down, the upper below and the lower above.’8 He said to him: ‘You saw a well regulated world.’ [He asked further]:...
ברכות כ"ח ב
When Rabban Johanan ben Zakkai fell ill, his disciples went in to visit him. ... At the moment of his departure he said to them: Remove the vessels so that they shall not become unclean, and prepare a throne for Hezekiah the king of Judah who is coming.
(Translation courtesy halakhah.com)
To answer your second question, this have no relevance as to whether anyone else's Near Death Experience has any significance. People often see what they want to see in Real Live Experiences as well, and people make them up all the time, so one should expect that same kind of behavior with Near Death Experiences, as well.
Those interested in the Jewish view on Near Death Experience (NDE) should see the videos from R Alon Anava. He was a secular Israeli, as far away from Judaism as one can, when he had a near-death experience in his thirties after experimenting with drugs.
He describes in great detail his experience of hovering over his body, seeing his whole life in front of him, being judged and found to be lacking, the pains he experimented and the chance he got to come back. He made tshuva, learned in yeshiva and now speaks about his experiences. Whether or not you agree with it, it is worth watching as it is a rare source of a deeply religious individual speaking about NDE and relating it to traditional texts. At a minimum he used this experience for the better, transformed his own life and likely many others.