Visa for a colombian person doing an academic exchange in sweeden

Hi i am from colombia and i need to get it for christmas. From september I will be living in Umea and I have some questions:
- Can I apply by post?
- Can I stay at a frined there or do I need to do an hotel reservation?
- In the list of document that I need to give to the embassy is a persobevis but since I'm from colombia I can not get one , so what I need to do?

Thank you