First, as a foreigner, you have the same rights and responsibilities at work as a Finnish employee, even if you do not have a residence permit. As an employee you have tons of rights to protect and serve you.
Second, always keep the documents related to your work, such as contracts, emails, and receipts. It’s advisable also to scan or take a photo of the documents, if they are on paper. Normally you should not encounter problems, but in case of dispute, you will need the documents.