Actually, only a couple of the cylons numbers are known.
http://en.battlestarwiki.org/wiki/Humanoid_Cylon
As for TV shows, seasons on most series used to be 24-26 episodes per year. That was during the 80's and 90's, but that's been sliding down where the number of episodes per series. It seems they've linked it to the show's performance now. Some shows only get picked up for 10-13 episodes per season, others can pull 20-22 episodes.
It's all about the budget. the 13 episode half seasons or pilot seasons most networks jump for is actually a hold over from the 80's when new series would get a pickup for 13 episodes and if it did well in the ratings for the first 7, the network would order an additional 13 for a full season. But if they didn't, the network would have 13-hours of filler material during their off seasons.