http://www.coolnurse.com/birthcontrol.htm
http://www.crisispregnancy.com/birth-mother/pregnancy-questions.html
http://www.epigee.org/guide/medfaq.html
yup.
There is no fool proof birth control -...
No. You are as protected during that week as when you have the ring in.
Using the ring is similar to the pill or the patch, you are protected 24/7 provided itis used correctly.
Unlikely. You should have your period during your pill free week. During which, your eggs are being released. However, anything is possible and it is not 100% fool proof.