Do I need to send diplomas with my application?Only if you are asked to. Some employers ask for a copy of your diploma at the beginning of the procedure; some recruit applicants without seeing it.
Should I supply references, letters of recommendation or proof of good conduct?
Employers normally ask for references or letters of recommendation.
All employers require proof of good conduct (i.e. whether you have a criminal record). Normally you need to be able to prove this for every job.