For anyone curious about these answers directly, the first symptom of vajra hell is a consistent increase of the defilements: delusion (ex pride and conceit), greed, and anger, despite practice that would decrease such things. The second question: vajra hell is much more insidious and difficult to deal with than normal hell, because the wisdom and merit required to extract oneself from it is equivalent to the ignorance of the deed that was committed. Vajra hell is only enterable when one has an enlightened master to guide them. When the individual does not listen to the enlightened master, this is due to ignorance. The depth one goes into this hell is equivalent to the difference between the wisdom for the master's advice versus the wisdom of the student. This also determines the length of one is in that hell (the third question). Now how does one escape from such a hell? The must accumulate good merits, good deeds, and reflect carefully on their past evil actions, specifically those related to the masters. Then, once there has been an accumulation of enough merit, one will be able to practice enough so that the wisdom that they have becomes equivalent to the wisdom of the original instruction of the master that they ignored (which caused them to go to hell in the first place). Then, once wisdom is acquired, the act itself is no longer an vajra evil deed, but just a normal evil deed, which may still result in hell, but at least one has the capacity to do normal practices that would lead them away from a trip to the normal hell.