1) Re: menstrual cycles
Yes, our menstrual cycles will "get out of whack" if/when we are stressed, but here is a bizarre fact; the cycles of women who are in a group and live/have close contact with each other will start to match. Some women will have shorter cycles while others have longer cycles.. until they are all on their periods at the same time!
2) Re: contraception
Better than the rhythm method, women should learn how to gauge their discharge. A woman's discharge will become thick, egg-white like and gooey when she ovulates. This is a better prediction of ovulation than the calendar method.
Remember, an egg is viable for fertilization for about 24 hours. Sperm on the other hand, can live about 4 days... So watch what you are doing 5 days before and 2-3 days after ovulation.
3) Inducing a miscarriage/abortion
Women in traditional cultures for centuries have known how to abort a pregnancy. Some acupressure points works, as do some herbs. It is well known that Queen Ann's Lace makes a good "morning after" tea. Here is a link to some info:
www.naturalmiscarriage.org