Proof of your qualifications is not usually required at the application stage. However, you will need to show original certificates if you attend an interview. Take photocopies of your certificates in case the interviewer requires copies. Qualifications obtained from non-Maltese education institutions, such as foreign universities, must be recognised. You can request this from the Malta Qualifications Recognition Information Centre (MQRIC), which is part of the National Commission for Further and Higher Education (http://www.ncfhe.org.mt).
References are usually required if the vacancy is connected with the service industry, finance and the like. A previous employer, a reliable professional or a parish priest could be a suitable referee. They usually confirm that the person in question is a reliable person who can be expected to perform this type of job without problems.
Letters of recommendation are only needed if the employer asks for them.