A followup to my iPad implementation. Here's how I get a new iPad integrated into my fold.
Sign In to the App Store
I disable auto-downloads because you may want to test an app before putting it on all your iPads. Other iPads tied to this account will grab the app at an unspecified time without telling you. Later we will set a restriction that will prevent a student from signing you out.
Get Your Purchases
Anything you've purchased with this Apple ID will appear on the "Purchased" tab in the App Store. A cloud icon means the app is not currently installed. Tapping it will begin a download. The App Store requires your password before this can happen, and that authorization will expire after a period of time. A student cannot grab any of this stuff if the authorization window has expired.
Set Up iCloud
Your iCloud ID is the same as your Apple ID. This enables document sharing (Documents & Data) between copies of apps and sharing photos quickly (Photo Stream). The mail/contacts/calendars/reminders stuff can be disabled. By default the iPad will backup user data when plugged into power. This only saves user created data. Apple automatically keeps track of what apps are credited to your account (or music/movies you've purchased) and you do not need to back them up.
Now to enable Restrictions. It's under General and you have to scroll a bit to find it.
By default, everything will be grayed out when you enter.
Tapping enable will prompt you to create a passcode. This is different then setting a passcode for the lock screen. If you ever want to change a restriction, you will need to enter this passcode. I would not recommend setting a passcode for the lock screen because inevitably students will figure it out unless you are really crazy about unlocking the devices for them. Unfortunately, there is no restriction to prevent setting a passcode for the lockscreen. Some clever student may do this to you. The iPad will have to be restored to remove the lock screen code.
The first group of settings will enable/disable a limited range of device capabilities. If you disable FaceTime and iTunes, their icons will disappear from the home screen. Enable them to make the icons return. Siri settings only appear on the iPad 3/4/mini. If you're really worried about students getting other apps onto the device, you can disable installing apps and re-enable when you want to add something. Though it's a bit tedious.
These are the restrictions I have set on my devices. I don't mess with content ratings because I've disabled the iTunes store entirely. Now scroll down to the account section.
Each of these will prevent a student from changing account information. The corresponding icon in the sidebar will gray out when you disable changes. It cannot be accessed without disabling the restriction by having the restriction passcode. You cannot remove the Mail icon from the homescreen, but with account editing disabled, the app will prevent the student from adding an e-mail account to the device.
Once you get a feel for what needs to be done, a device can be set up in about 10 minutes. App downloads take time and you'll need arrange them on the home screen, but the settings portion is easy. You'll need to do a few things like sign in to Dropbox (and give it access to photos) if you've installed it, enable iCloud in apps if they aren't by default, but that can be done quickly. Once I have all the apps downloaded I launch each one to make sure it's ok. I have less than 10 apps on my student iPads.