I believe the B777 can land with Flap 25 or Flap 30 anyway, so it won't get any sort of config warning on the way down like other ac will. I guess Flap 30 just makes it easier to stop at the bottom, ie for shorter runways
It can but the normal setting for a manual landing is F25. You'd opt/be required to use for F30 for a variety of reasons one of which is indeed shorter runways, but Gatwick's main runway is not that short, even with the displaced thresholds (and for interests sake in some circumstances you can land the 777 using F20).
Nothing wrong in taking the last bit of flap right at the bottom.
That would very much depend on who you fly for and what you mean by "right at the bottom" - taking final flap below 1000' would certainly be against some airlines stabilised approach policy and could well earn you a phone call. Taking final flap over the concrete, as the OP claims he saw happen, would probably qualify for an interview at some airlines....without the tea and biscuits.
edited to add: Magic90 - you're very welcome, good luck with the licences
