maybe im wrong but i was under the general impression that the dalai lama was the spritual reincarnation of the last dalai lama. also its not a bhuddha its THE Bhuddha ie the original indian one from 8thC BC if thats who you are talking about since as far as i know all sentient beings who receive enlightenment while alive and then die become bhuddhas and dont reincarnate they go to the second level of heaven rather than the first and then subsequently back to earth, but its not like im hot on the subject.
The Dalai Lama is a reincarnation/rebirth [although the two have very different meanings if you use reincarnate in the western sense] of the Buddha of Compassion, I believe. There is no One buddha according to Mahayana Tradition, where anyone is theoretically capable of becoming a buddha - this may be where your notion of all enlightened beings becoming buddhas comes from. The Theravadans believe only certain people can become Buddha's, that is a person who not only is enlightened but can preach the Dhamma [a broader definition than Mahayana tradition], and that the last Buddha was Siddhartha, Gautama, or the many other names he has been called.
There is no heaven or hell in Buddhism, either in Theravadan or Mahayana (although I'm not sure about Mahayana, the very concept of Heaven doesn't comport with Mahayana teachings). While the Buddha spoke of Devalokhas, sentient beings on a different plane, this wasin his discourse about other worlds and planes - they pose no danger to us, are not ghosts of any sort, and do not fit into any Western notion of existence.
Although Mahayana has been hinduized, due to cultural and Hindu influences, it doesn't differ much. Often, you will find Mahayana Buddhists praying to Hindu gods, or at least putting faith into their existence - ironically, though Hinduism and Buddhism are very similar, the fundamental differences - Buddhism is non-theistic and believes in no soul, while Hinduism is the opposite - make this combination awkward in my eyes.
Anyhow, the reason I view Tibetan Buddhism as wierd is because of this strong search for permanance of the Buddha - this continual reincarnation is at odds with the cessation of Karma that a Buddha achieves, and also is at odds with the Buddhist notion of impermanence, which strangely the Tibetans are proud to demonstrate through the creation of eloborate sand mandalas and the subsequent sweeping away of the sand and their hard work.
By the way scientific studies have argued that 'enlightenment' is actually what happens when you meditate your brain down to a virtual cease in a certain type of reaction, and then one happens and they cause others to happen and you have a cascade that is senced in conciousness as what bhuddhists recognise as enlightenment
I don't know where you read this, but I'm sure you can see how ridiculous this sounds - scientists have yet to figure out why a collection of sounds, a melody, can invoke memories, tears, and various emotions, and put forth that they can attempt to describe what the Buddha himself declared indescribable? Who is the enlightened person they have studied in order to formulate this hypothesis?
Regarding past life regression, prodigies, and the like - Buddhists, at least the monks that I was fortunate enough to question at great length, explained this as a characteristic of rebirth. Rebirth is not the transferrence of a soul to another body, but the transferrence of an energy, we'll called the mind, to simply another physical housing - while we consider death as an end, it is not much different than the "death" and consequent rebirth that we undergo every second. It is only because of the relatively drastic change (when compared with the change from one second to the next) that gives us a sense of finality - are you the same person you were a 5 years ago? Where is that body in the picture you took at your middle school graduation? It gone. How is this any different?
