It depends on the norms of your university. In some cases, it can go in the methodology, in some cases the discussion or conclusion. In other cases, both, but discussing different types of limitations.
Medication errors and adverse drug events in a UK hospital during the optimisation of electronic prescriptions: a prospective observational study, Is it a qualitative or quantitative or both . Pls can anyone help
Typically past tense, but you should have a look at past dissertations from your uni to check what the institutional norms are. You can also ask your research advisor/supervisor.