Analytics Software

Hello Guys,

I am trying to design a new rpd for a BI project. I am waiting for the reporting requirements after which I can start analyzing and desing my model.My concern is in the database some of the tables do not have primary keys defined and even the PK-FK relationships are not defined correctly. I was asked to design the data model in the database. I understand that I have to figure out whether the existing joins will be able to generate the desired report. But if the current joins will not give me the desired report I guess I should find out the right joins between tables and the right PK-FK relationships.
(1) Once I do that how do I implement that model in the DB? Is that something that has to be done by the ETL team or the DB team?
(2) Else If I have to do it do I have to modify the existing tables or create new ones with new PK-FK relations?
(3) Cant I just import all the tables in the Physical Layer and then make my PK-FK joins there?

Please let me know.
Thank You.