The same trip prices the same way
Rates live in a catalog you control, so the figure does not depend on who happened to answer the enquiry.
In the box
The same catalog that prices an enquiry prices a booking, so the number never depends on which screen you were on.
What changes
Rates live in a catalog you control, so the figure does not depend on who happened to answer the enquiry.
A quote line points back at the rule that produced it, which is what makes the price defensible when a client asks.
A surcharge that is visible as a surcharge is one you can explain. A surcharge folded into a total is one you have to reconstruct.
They are snapshotted when the quote goes out, so editing your card tomorrow does not silently reprice a quote a client is still reading.
Questions
Yes. Edit the quote before it goes out; the override is recorded next to the rate it came from, so the figure you sent stays explainable later.
You are told the rate is missing rather than handed an approximation. A plausible number you cannot defend is worse than no number, because you only find out which it was when the client queries it.
No. Your rate card is your data. Our subscription price and your client pricing are unrelated, and nothing we ship edits the rates you configured.