when hosting , keep power on on pc?
when hosting , must i never power down the pc?
Incorrect, Sia allows for 5% (IIRC) downtime for maintenance before your score is adjusted negatively. So you are allowed to power down your computer for a small amount of time every day, for example.
Yeah and that may sound like it's stringent but it's really not. You could have your PC off for 72 minutes a day and that's plenty long enough to reboot for an update or whatever.