Buddhism - Death/ rebirth?

Refuge is the door to Buddhism. Bodhicitta is the door to the Mahayana. Initiation is the door to Tantra. As for "beliefs of Tantra" - there really isn't anything that radically different from any other form of Buddhism. Tantra is "merely" the fastest method by which one can achieve the goal of complete enlightenment, Buddhahood. A Tantric Buddhist most certainly seeks refuge and generates bodhicitta. Also know that in Buddhism one recognizes ones own suffering and seeks refuge from this suffering (seeks refuge) but recognizes all sentient beings suffer, so generates the wish to be of benefit to others (generates bodhicitta), but, recognizing that only a Buddha can truly benefit others, one resolves to become a Buddha oneself. He or she might search for a path that leads to Buddhahood and only the Mahayana path leads to Buddhahood. There are two divisions of the Mahayana - the perfection vehicle and the tantra vehicle. The end result is the same: Buddhahood. But tantra is much, much faster because the esoteric methods are much more profound. So one would seek initiation into any of the four classes of tantra...But, beware, there is a system of study and practice that must be understood by the practitioner, and adhered to, lest he or she lose his or her way. He or she would at least have established some familiarity with renunciation, bodhicitta, and the correct view of dependent origination. This is why it is critically important to have an honest-to-goodness teacher of tantra, a suitable guide who can keep you on track. And these are as difficult to find as stars in the daytime.