In iCloud settings, you can select exactly what you would like to have in your iCloud Backup. Go to **Settings** → **iCloud** → **Storage & Backup** → **Manage Storage** → **This iPad**. There you can enable/disable various data sources that are able to be backed up by iCloud Backup.

For example, you can leave all the apps selected and simply disable the Camera Roll backup. Attempting to disable the Camera Roll backups after completing at least one backup will prompt you before deleting the existing Camera Roll backup:

<img src="https://i.sstatic.net/idlkb.png" height="100" title="iCloud Backup: Camera Roll">
<img src="https://i.sstatic.net/IOWgH.png" height="100" title="Alert: Turn Off & Delete">

For more granular control of exactly what is synchronised to iCloud other than app and device data, you can view and modify iCloud services sync settings by going to **Settings** → **iCloud**.

At the time of writing, there are 8 iCloud services that synchronise data: Mail, Contacts, Calendars, Reminders, Safari, Notes, Photos, and Documents & Data. Each one of these services can be enabled/disabled independently. Tapping **Documents & Data** gives you granular control over exactly which apps can sync data through iCloud.

<img src="https://i.sstatic.net/pfiYH.png" height="250" title="iCloud Services"><img src="https://i.sstatic.net/tUUW7.png" height="250" title="iCloud Documents & Data">

You can view exactly how much content is on your device by going to **Settings** → **General** → **Usage**. There, it details the cumulative space required by a certain app or service. Tapping on an app/service shows a breakdown of that space requirement. For example, tapping iBooks shows that the app is just under 60 MB, with the Documents & Data being almost 1.5 GB. If you selected to backup this app under iCloud Storage & Backup settings, then only the Documents & Data would be backed up - the app itself is not backed up by iCloud Backup. The second example shows an app where this is more useful: Real Racing 3. The app itself is almost 1.5 GB, however the data is 1.5 MB. During an iCloud Backup, only the 1.5 MB of app data is backed up. Since the app resides on the App Store, it is unnecessary for this to be backed up; during an iCloud Backup restore, the app is re-downloaded from the App Store.

<img src="https://i.sstatic.net/JTjzd.png" height="185" title="Usage"><img src="https://i.sstatic.net/CPVPP.png" height="185" title="iBooks"><img src="https://i.sstatic.net/y1FpU.png" height="185" title="Real Racing 3">

iTunes shows you a brief breakdown of the content of your device as well. Connecting your device to iTunes (either by USB or iTunes Wi-Fi Sync) and going to the Summary tab shows you a graphical summary of the types of data, however (unfortunately) it does not give much detail about exactly what is in each category like the iOS Usage page does.

<img src="https://i.sstatic.net/BmNaY.png" width="500">

You mention that you don't want this content to sync to other devices - iCloud Backup will not restore data to other devices unless you specifically request it to. However, Photo Stream will upload your camera roll to iCloud and sync it to other devices. You can disable Photo Stream in **Settings** → **iCloud** → **Photos** → **My Photo Stream**.

<img src="https://i.sstatic.net/e9nS2.png" width="250" title="My Photo Stream">