Once you go past flaps 20, boards up, you'll get the warning, just like the 75/76. They feel a lot like on the 757, the first half of the handle pull will give you a small amount of rumble, but then the second half (full up) will give you quite a bit of bounce, most of us rarely use full boards, you'd have to be really high and hot or getting slam dunked to need them.
But... just like in the 757, the 777 is a bit of a Kite and doesn't like to come down too quickly, even with the gear out. I can honestly say, I've only seen guys get behind by being too high/hot on the path, never too low/slow.
On the automatic retraction, I don't think (never tested it) they will stow when the power comes fully up, only because many, many times I've had to say, "You've still got the boards out..." once stabilized after a slam dunk, but I usually say it as soon as the thrust levers start moving up and it's obvious he's forgotten. So they may stow, if the thrust levers come far enough fwd.
This all usually happens about the maker, usually when you're throwing the gear out, more flaps, spinning the speed back, arming the APP button, etc. switching over to tower, and they throw a runway change at you too...and some guys will go heads down to try to load it in the box.
I gave up taking close in runway changes a long time ago. We still get paid by the minute, I'll roll to the end, thank you, and take my time taxiing back...unless I have a commute home to catch of course, then it's the ol' SWA Game ON!
(can we get opposite direction to the inboard?)