You need to specify what pill you are talking about.
yes you have to keep taking the pill that's the only way your protected. if you stop taking the pill you can get pregnant.
No after a week you are protected.
If she's taking the pill according to instructions that risk is very, very small.
Yes a girl can get pregnant on the pill even if taken correctly..only is 99.9% the 1% can happen to any person who takes the pill and is sexually active.
Yes. If you miss a pill, you need to take it as soon as you remember, but there is still a chance you may get pregnant.
A hormonal imbalance.
You can get pregnant after you stop the pill.
You can get pregnant whilst on the pill, but it is very unlikely.
If by reminder pill you mean the active pill then yes you can become pregnant.
If you're pregnant, then your periods will stop. Also, if you are pregnant, you SHOULD NOT be taking the pill.
If the girl is taking the pill perfectly then it is 99% effective. If she misses any pills her chance of getting pregnant increases. If you are not too worried about getting the girl pregnant because shes on the pill then don't use a condom. But if you are worried at all then definitely use a condom. Overall i recommend using a condom every time.