You can also go to who's online. That keeps you logged in forever as it reloads every 60 seconds. I think Amiga.org automatically logs you out if you don't do anything for a certain amount of time. Who's online gets around this.
I do not think so, at least not within a 12-24h time span, I am logged in 24/7 and I am just at the index.php when im at work or away, I only get logged out if I switch between my static IP's and as long as I do not change my global IP I do not get logged out even if I restart the computer.