[Azselendor]

Dirk Benedict was actually appraoched originally by Bryan Singer to play a 50 year old starbuck, with no changes to the character (thus creating someone who is kinda tragicly too old for the way he lives). He was later approached by RDM to play a cameo in season 3 (I suspect in Hero), but passed.

As for the other 5 models, I suspect that since the cylons are a young civilization, those 5 are still teenagers and are locked up in brother cavil's basement.