Yes. In reality, if you're even a few hours late taking a pill, you could be pregnant, thought that isn't as likely. You should talk to a doctor. If you're not good with remembering the pill, you could also ask your doctor about the patch or shot.
It all depends on which week you missed taking your pills and when you're ovulating. Usually week one and week three you are at the highest risk of getting pregnant. Follow the instructions for your birth control on what to do if you missed two or more days.
Yes, you very possibly could be. It's always best to use a condom as a back-up even if you're on the pill and haven't missed taking any, because birth control pills are not 100% effective.
The quick answer is yes. Even if you take your birth control every single day you could still become pregnant as it is not 100% effective. Also, unless you take your birth control pills exactly 24 hours apart you lower the effectiveness. The only way to 100% prevent pregnancy is to not have sex.
If you missed the birth control pills in week 2, then this is a significant possibility. If you missed the pills the first week, it is less of a risk. If in doubt, take a pregnancy test or see a doctor.