I'm still working out the best padding to use in mine. I'm also not 100% sure they are exactly the right size (maybe a little large) so am trying with different thickness of socks.
I have slept in them a couple of times (cheating I know
)
As to standing and walking, no more than a few minutes at a time before I have to sit down. Getting less cramping now though.
A little piccy of me standing in them with my work trousers on.