Hi

I am a bit confused on which words to use for these sentences.

For example, if I wanted to say
"It was her"
Do I say:
Это была она
or
Это была ее

Also if someone asked a question such as
"Ты говорил с ним или мной?"
"Were you talking to him or me"

If I wanted to say "To you" Do I just say "Ты"? or "Тебе"? or what?

And one last thing. If someone asked
"Кто говорит по-английски?"
and I wanted to say "I do"
How do I say that?

Thanks in advance