Dragon Familiar feat from the Draconomicon- Silver Dragons

[UltimaGabe]

Hey, could someone possibly tell me the prerequisites for the Dragon Familiar feat from the Draconomicon? Specifically, the caster level prerequisite?

And, if possible, what level/s a character must be to have a Silver Dragon familiar, and what age categories the dragon can be at what level?

 

[Derren]

The dragon is always a wyrmling and when it advances it stops beeing a familiar.