A) Can you please help me differentiate between "before" and "until"
I could not get to work before/until 5:00 pm.
I will not be able to see you before/until tomorrow.
You will not be able to speak english fluently before/until you fully
In these sentences they mean almost the same thing:
I could not get to work before/until 5:00 pm. This means I was not able to get to work any earlier than 5pm. I was not able to get to work at 4pm or 4:30 pm or 4:55 pm.
I am not able to see you before/until tomorrow. These mean I am not able to see you any earlier or sooner than tomorrow.
The last sentence was not finished but it appears that they also mean the same thing for both.
I hope that helps