Hi there, check out the archives for info as most of that is pretty up to date.
The essay questions seem to be a variation on a theme, regardless of which FB you attend. All seem to want you to talk about how you as a pilot would improve cost efficiency/customer relations/safety etc. We had to imagine we were writing an article for 'High life' magazine about the above. Not too tricky if you memorise a few facts and prepare a few ideas you want to suggest before you go in. You have an hour to write.
The interview is fairly straight forward. All very pleasantly conducted but still a thorough grilling which you can't do that much to prepare for. From what we could work out, the format is pretty much the same regardless of who you see. The pilot starts asking questions first. A few on BA and why them in particular and why you in particular. Most of the questions expand on your application form, or rather certain bits of it. Learn it well as in my interview they focussed virtually all the questions on two answers I had given and came at them from every angle. The HR questions were a lot deeper, asking about how you take criticsm with egs, when you were at your most flexible, best/worst time of your life etc. Things that you really can't predict. By talking to the others at my Fb, it seems they all ask the same questions but word them slightly differently. But generally there aren't any you can't answer, it's just whether you give the answers they want to hear. It lasts between 1 hour and 1.5 hours but it really does fly when you are in there. Try and talk as naturally as you can and don't lie as you will only end up tying yourself in knots. They know exactly when you are expanding on the truth so just try and answer their questions as best as you can keeping as close as poss to the truth.
The only thing that was different from what was expected was the group exercise. We were each given a card with 4 or 5 separate lines of information and a box of things in front of us, plus a map. The task was to plan a route out of the desert by using the info we were all given, and then choose 10 out of about 25 items from the box which we would take with us. There is bound to be some disagreement what items you choose but don't worry about it too much as although you do have to sum up what you did at the end they are not really that interested in what you chose. Most important to remember is to make sure you contribute some but don't take over the group, use everyone's names and talk loud enough so that the panel can hear, but try and forget they are there. Get a timekeeper to announce time every 5 mins and make sure you don't spend too long on the items and not enough on the route or vice versa. The group ex. is in the afternoon so make sure you become quite friendly with the rest of your group throughout the day as it makes the whole thing work easier.
That's about it really. Don't believe them when they tell you you'll hear within 7-10 days. I am still waiting and from what I can gather I am not the only one. I think a more reasonable estimate is about 3 weeks.
Good luck!!