Reported Speech

1) Peter said that he couldn't live on his basic salary and he would have to offer to do overtime.
2) I said that he was always making terrible mistakes, and he should to be used to it at that moment.

'At that moment' is a little confusing in the previous sentence. It's not clear what it refers to. Should he be used to making mistakes specifically at that moment or did you say this to him at that moment? Another phrase that could make sense there is 'by now.' Perhaps that's what you mean.
3) They earned three times as much in that factory as they would in their own country.
4) Paul said that he had gotten a job on an oil-rig. 'Got' might be British English, not sure.
5) Mary said that she would like to speak to Susan.

Well done. The errors are minor.