Culling, Relationship Culling & Decay: Current Status

@luthienrising: Thank you for your answer.
@leo3487: Thank you, too. I'm playing with aging off. (I hope this is the right description. Sorry for my English.) There are some of the 800 sims used for NPC roles already. That's not too bad. But what I fear is: even favourite sims could be culled if I add some more (if the limit still is 800).