How many types of Buddha are there? What are the pre-requisites for becoming these different types of Buddha?

There are three types of Buddha: Arahat Buddha, Pacceka Buddha, and Sammasambuddha.

All three are born human with the highest virtue and supernormal wisdom, they develop from being a Bodhisatta, develop spiritually over countless aeons, and are motivated by compassion.

The first is a disciple who perfects the Paramis over hundreds or thousands of lives, achieves the pre-requisites for becoming an enlightened being, meets the Buddha or a disciple, hears the teaching, grasps the teaching of the four Noble Truths and becomes an Arahat.

The second fulfils the 10 Paramis over two cycles, appears when the teachings are lost and beings are living in ignorance, becomes enlightened on their own, and lives in seclusion as a hermit.

The third fulfils the 10 Paramis over three cycles, becomes supremely enlightened by hearing and understanding the Dhamma from previous Buddhas, enlightens others and makes significant impacts on world history.

What is a 'Bodhisatta'? How many types are there? What are the requirements to become a 'Bodhisatta'?

The term ‘Bodhisatta’ (or 'Bodhisattva') means a would-be Buddha, or a future Buddha, in other words, someone with all the exalted spiritual perfections leading to supreme enlightenment, and destined to achieve Buddhahood. There are three types: those leading to Arahat Bodhi, those leading to Pacceka Bodhi, and those leading to Sammasambodhi.

In the case of all three types they must achieve enlightenment through emancipation and the liberation from worldly bonds. To become a Savaka Bodhi one sacrifices material possessions and their pleasures for the welfare of others. To become a Pacceka Bodhi, in addition to this, one sacrifices parts of the body for others. To become Samma Sambodhi one also sacrifices one’s life.