i think it updates daily or so, not sure thats just my estimate from my own use.
you can easily add an online .ics calendar, probably other formats as well.
settings > configure kalendar > accounts > add account (under calendar, not under contact books) > ical calendar file > just paste the url in the ‘file name’ field and give it a name. it works
one problem is that the panel calendar widget is hard coded to only show max 5 events per day :((