Hello, I'm here

You're all very well trained and have answered the questions correctly. Go to the top of the class!!

A couple of things, don't rely on Fast Track. It's barely operational and as others have said often has the longest queues. That's because they let everyone else in

The boarding light will show in the lounge to confirm you should go to the gate. Yes, it will sometimes flash up too soon but it can also be correct. I recently took two flights and both were actually boarding by the time I got there. Both were on Pier 6 - Gates 101-113. It's a fair trek over there so allow yourself time, and gates 61-63 are quite a trek too.
BA mainly use gates 54, 57-63 and 104-107 for international departures. Gate 55 (A-J doors) is domestic only.

Priority boarding is on all flights now and most of the time this is done. We do enforce this on some flights, depending on how full the flight is, staffing levels, language problems, etc. I tend to find on long hauls most people are pretty good at waiting until called, the short hauls are usually a bigger problem.

Enjoy LGW