Probably not,unless what she thinks is her period is actually implantation bleeding.
yes very very likely.
Yes, this is an indicator of pregnancy.
I have before my period, I start my period for 3 days then My period was stop after my period for 3 days, I want to know what happened to me?
Some do, some don't.
Yes, it is not as common to get pregnant while on your period, but you still can get pregnant. Sperm can live inside a women for a few days and it is definitely possible.
She will have what is called a missed period. Where you don't get your period for that month. And if that happens then you should take a pergency test to make sure that she is pregnant.
It is very unlikely but there is always a small possibility