i justt wouldnt be suprised if the five cylons are an earlier model.
and not all cylons are young.. remember dean stockwell's character.
Are we certain things we have seen so far will not be dismissed later at writers convenience. IE D getting sick so she can't be a cylon... then writers wanting her to be cylon either dismiss that or write in something to explain it.
we just saw recently that cylons indeed can get sick and die from human diseases.
they may be stronger then a human and thus more able to withstand certain physical punishment but they indeed can get sick.