I can not help you with all devices as I came here to figure out how I can sync my iCal from Mac to my iPad not using icloud ( I still have OS10.6)....but I can easily sync my android phone with my iCal on Mac using "SyncMate". It's a software that I run on my Mac and syncs my android callendar with my iCal with out any need of the hideous google calendar. Hope that helps in some extend.
I've been using iCloud since it's inception as "mac.com" or whatever it was called. I've been able to Sync Outlook Exchange Calenars to my iMac, iPhone and iPad. However, I cannot get iCal (when viewed in iCloud) to display Exchange or Google Calender items.
It's odd, all other Mac versions of iCal are happy e.g. iMac, MacBook Air, iPad Air, iPhone etc. But nothing when I login to icloud.com and look at the iCal there.