Did the Buddha speak Pali? Are the suttas his word verbatim? Was Pali the language spoken during the time of the Buddha, and would he have spoken this language?
Are the suttas contained in the Pali Canon verbatim what the Buddha said, or would things have been changed due to centuries of oral transmission?
The Buddha likely spoke in several dialects that were quite similar to Pali. He was immensely well traveled for his time, so in his travels he likely adopted the native dialect to be better understood by the locals. His words were only a small part of his teaching - his enlightened presence and conduct were likely better vessels of his teaching.

The Pali canon is a consolidation of his talks, created only after his death. The content is very likely the same, but the rendition is only as Ananda and other disciples remembered him. The standardized repetitive form was created as an aid to rote memorization and oral rendition. There was certainly doubt in their minds as they set down the teachings that they'd not be able to replicate the vastness of the Buddha's being in mere words, but all the same they resolved to make a sincere effort, and the Canon that emerged was a result of seven months of deliberation.


See https://en.wikipedia.org/wiki/First_Buddhist_council

Pali (Pāli) is a Prakrit native to the Indian subcontinent. It is widely studied because it is the language of many of the earliest extant literature of Buddhism as collected in the Pāli Canon or Tipiṭaka and is the sacred language of Theravada Buddhism.
Many Theravada sources refer to the Pāli language as &quot;Magadhan&quot; or the &quot;language of Magadha&quot;. This identification first appears in the commentaries, and may have been an attempt by Buddhists to associate themselves more closely with the Maurya Empire. The Buddha taught in Magadha, but the four most important places in his life are all outside of it. It is likely that he taught in several closely related dialects of Middle Indo-Aryan, which had a high degree of mutual intelligibility. There is no attested dialect of Middle Indo-Aryan with all the features of Pāli. Pāli has some commonalities with both the western Ashokan Edicts at Girnar in Saurashtra, and the Central-Western Prakrit found in the eastern Hathigumpha inscription. 
Whatever the relationship of the Buddha's speech to Pāli, the Canon was eventually transcribed and preserved entirely in it, while the commentarial tradition that accompanied it (according to the information provided byBuddhaghosa) was translated into Sinhaleseand preserved in local languages for several generations. In Sri Lanka, Pāli is thought to have entered into a period of decline ending around the 4th or 5th century (as Sanskrit rose in prominence, and simultaneously, as Buddhism's adherents became a smaller portion of the subcontinent), but ultimately survived. The work of Buddhaghosa was largely responsible for its reemergence as an important scholarly language in Buddhist thought. The Visuddhimagga, and the other commentaries that Buddhaghosa compiled, codified and condensed the Sinhalesecommentarial tradition that had been preserved and expanded in Sri Lanka since the 3rd century BCE.

Source: https://en.wikipedia.org/wiki/Pali
See also,  http://www.vridhamma.org/Pali-Overview-94-Seminar