mjohn- this has hints and some detailed spoilers.
maximus- I believe there is a topic about htis stickied to the first page called "questions about the ending" or something a long those lines but to answer your questions.
1. For the most part your population cannot go over 90. Unless you have 89 people and have twins or triplets or an island event.
2. There is pretty much nothing you can do about it.
3. nope only the 16 and that is it.