Short answers, pulled from the story.
In the Pali Canon, a Buddha is described as one who has reached awakening or enlightenment through their own efforts and insight. This state means they have found the path of cessation of suffering known as duhkha.
The Seven Buddhas of Antiquity include Vipassī Sikhī Vessabhū Kakusandha Koñāgamana Kassapa and Gautama. Following these seven a Buddha named Maitreya is predicted to arise in the world according to the Chakkavatti-Sīhanāda Sutta.
Emperor Ashoka visited Nigali Sagar in 249 BCE and erected a pillar dedicated to Koñāgamana Buddha. The inscription on this pillar records his visit and the enlargement of a stupa.
Mahayana Buddhism considers any Buddha to be a transcendent being with extensive powers who is all-knowing while Theravada Buddhism views a Buddha as having limitations of a physical body. Mahayana Buddhism defends a kind of docetism where Gautama Buddha's life on earth was a magical display which only appeared to have a human body.
Five primary Buddhas known as the Five Tathagathas include Mahāvairocana Aksobhya Ratnasambhava Amitābha and Amoghasiddhi. Each is associated with a different consort direction aggregate emotion element color symbol and mount.