Jesswaszr summed up everything I was going to say. If you take antibiotics or have vomiting/diarrhea at any point, use a condom for back up. The pill alone is 99.9% effective IF taken properly. Always take it at the same time, and follow the instructions given to you by your health care provider. The pill alone won't protect you from STD's.
Hello, when first starting the pill it may take your body at least a month to get used to the new hormones. I had my period for a month when I first started. It is common, but keep an eye on it and if it lasts over 2-3 months I would suggest talking to your doc because you may not be getting enough hormones. The other thing you mentioned about having unprotected sex and him pulling out, firstly the pill is not really working right away need to give it time for the hormones to be in your body and the other thing is it does not matter if he pulls out or not there is a chance of pregnancy either way. Just be careful and use condoms for the first month or so and then do what you want. Anyways hope that helps some