who sang in the recorded version of it?
Edwin Othello Excell is one of them
Amazing Grace
Where Edwin Othello Excell sought to make the singing of "Amazing Grace" uniform throughout thousands of churches, records allowed artists to improvise with the words and music specific to each audience. AllMusic lists over 1,000 recordings – including re-releases and compilations – as of 2019. Its first recording is an a cappella version from 1922 by the Sacred Harp Choir. It was included from 1926 to 1930 in Okeh Records' catalogue, which typically concentrated strongly on blues and jazz. Demand was high for black gospel recordings of the song by H. R. Tomlin and J. M. Gates. 
who wrote the last verse of amazing grace John Newton is it a poem? It is a Christian hymn
wiki:1639305
Amazing Grace [SEP] Recorded versions
I had marched, I had voted, I had gone to jail on political actions and worked for the candidates I believed in. The war was still raging. There was nothing left to do, I thought ... but sing 'Amazing Grace'." Gradually and unexpectedly, the song began to be played on the radio, and then be requested. It rose to number 15 on the "Billboard" Hot 100, remaining on the charts for 15 weeks, as if, she wrote, her fans had been "waiting to embrace it". In the UK, it charted 8 times between 1970 and 1972, peaking at number 5 and spending a total of 75 weeks on popular music charts.