It looks like you need:

Documentation of the pension
Birth certificates for everyone coming in under the program*
Marriage Certificate if married and bring in a spouse*
Police records check for all coming in over 18 years old*

* Documents must be certified by the nearest Panama Consulate or Embassy.

passport valid for at least six
health certificate, done in Panama
applications must be in person
takes about two months
Need to be in Panama for at least four days to apply, and another four days to pick up the visa