yes.
Yes
Yes you can.
Yes.
Yes.
I don't get it, but girls can't get girls pregnant, fullstop.
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.
Probably not,unless what she thinks is her period is actually implantation bleeding.
If she was pregnant it would be highly unlikely for her to get her period, however if she wasn't pregnant she should still get her period like normal.
yes very very likely.
Yes, all girls have periods. If you skip your period you are probably pregnant. Periods tell you that you are not pregnant.
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.