1. last but not least. be a friend to her. Be a good companion and always be there for her.
- What does "last but not least" mean here? and I think "be a friend with her" is better, right?
"Last but not least" means that the speaker has given other instructions and that is the last one, but that this one is definitely just as important as the other ones. "Be a friend to her" is what I would use in this context. Perhaps another teacher could tell you more about the grammar rule behind this ![Smile [:)]](/emoticons/emotion-1.gif)
2. - Is there any way that I can help her? (a)
- Are there any ways that I can help her? (b)
- I think (2b) is more grammatical, right?
2a sounds better to my ears.
3. Can you keep dating her knowing what she did?
- I think "...............her while knowing.......?" is better, right?
Both versions would be acceptable. I would insert a comma between "her" and "knowing" in the first version, though.