What issue are you having with settung up your calendar? You can check which account your calendars are associated with by going to Settings>Mail,Contacts,Calendars>Default Calendar. Each calendar will be listed under the account they are associated with. iCloud calendars are listed under your iCloud account name.
Also, I don't know what in what context you saw the term iCloud ID, but using the term iCloud ID is more specific that saying Apple ID. An iCloud ID is the Apple ID used for your iCloud account, which may be different than the one you use for other services. I suspect Apple was trying to be specific when they used "iCloud ID".
I think I figured out that iCloud must have 2 calendars associated with it that is called "home" and "work". You just have to know that I suppose. Also, my real "home" account is a Pop5 and its calendar cannot be synced. Unlike with my iPhone, neither can my school gmail account.
What i was saying is Using the term iCloud ID is completely different that saying Apple ID although you have to figure this out on your own because Apple uses them as interchangeable when setting your iCloud up. In other words, you can share an Apple ID amongst devices but back up each on a different iCloud. It would be nice if Apple would use these terms consistently. At one point my wife and I merged contacts and then she deleted all of mine thinking she was deleting them off her phone but really she was deleting them off our shared "cloud". I had to get my old phone and manually re type each one in. Also, I had to experiment that I could create another iCloud account and keep the same Apple ID for the store purposes. This is just one example of where Apple just leaves you to try it and hope it works.
Don't get me wrong, I love my iPad(I am on my second one) and iPhone. I just wish file manipulation and maintenance was not so clunky--going through iTunes instead of dragging all my files into a folder. Backing up multiple devices on one computer is an adventure. Also, trying to have multiple computers, multiple devices, and multiple users in the same household and keeping that all straight, woo! But I digress. I got the calendar thing figured out.
I appreciate your help.
Use a different Apple ID for iCloud, iMessage and FaceTime. Use the same for iTunes and App Stores. Back up the 2 devices seperatlly into iCloud. If you want to backup both devices in iTunes also (recommended), you have to have a different device name. Go to Settings>General>About to change it if it needs.