Form showing relationships

I'm two days new to customizing CRM and am struggling a bit with configuring a form.  Here is my scenario for a case tracking system:

1. A Person can be related to 0 or more Cases.
2. A Person has a "Relationship" to a Case.  Primary is one of the valid values.  Things like parent, sibling are other options.  
3. A Case can be related to 1 or more Person.

I need a Case form that shows the Name and Address Info from the Primary Person, together with case fields.  When opening the Case Form I see all the fields for the Case Entity.  

Question 1:  How do I get the Person fields from the related Person record?

Question 2: Next step in complexity, the Person info should only be for the Person record where Relationship = Primary.

Thanks for help in any form!