There shouldn't be a problem with this at all. Simply connect the devices and set them up as normal. I have an iPod, iPad, and several iPhones that sync with my Mac and I have not encountered any problems.
As far as using different email, contact, and sync info, you can set up all of that on the actual device itself in "Settings" > "Mail, Contacts, Calendars".
Syncing with iCloud
If you will be syncing email, contacts, and calendars using iCloud on each device, be sure to uncheck the following in the "Info" tab in iTunes:
-"Sync Address Book Contacts"
-"Sync iCal Calendars"
-"Sync Mail Accounts"
Syncing without iCloud, Using Sync Data from Your Mac
If you will be syncing email, contacts, and calendars using the info that is on your Mac, check off the following in the "Info" tab in iTunes, and then select which email account, contact list, and calendars you want to sync:
-"Sync Address Book Contacts"
-"Sync iCal Calendars"
-"Sync Mail Accounts"
Syncing Content from the iTunes Store
As far as syncing audio and video that was purchased from the iTunes Store, you will need to enter the proper account information on each device. This can be done in "Settings" > "Store". Changing the Apple ID in the "Store" settings will not affect the Apple ID used for iCloud.
There is no need to log in to individual accounts, at least with more modern versions of OS X. You can set access privileges for managed accounts from within the Users & Groups pane of System Preferences without leaving your own account.
By selecting the Other tab in the Parental Controls dialog you can even enable Remotely managing parental controls.
Upon further clarification by Cra, it seems that Apple's file quarantine system is causing the difficulty. Starting with Mac OS X 10.5, files downloaded from the internet are quarantined and checked for safety.
Applications that are downloaded must be approved the first time that they are run, and only the owner of the account used to initially download the software can grant that approval.
If you have multiple user accounts on your Mac, the user account that downloaded the file is the only user account that can remove the quarantine attribute to the file. All other user accounts can open the quarantine file, but they will be presented with the quarantine dialog box asking "Are you sure you want to open it?" every time they open the file.
ᔥ Apple Knowledgebase:About file quarantine in Mac OS X v10.5 and v10.6
Make sure that you download software updates using your administrator account and that you open and approve the software from your account before making any adjustments (which may not be necessary at this point) to the Parental Control settings. It may be necessary to disable automatic updates in Firefox.
The quarantine system works by attaching an extended attribute to a downloaded file. If absolutely necessary, you can remove this attribute using the terminal
Enter the following command, replacing appropriately:
xattr -d com.apple.quarantine /applicationPath/<applicationName>.app
See also: Stack Overflow: How do I remove the “extended attributes” on a file in mac
Best Answer
Apple Configurator includes a feature that allows you to select an app to 'lock' a supervised device to. When supervising a device, you can Lock to App and the iPad will be unable to escape from the app. This feature will prevent all hardware buttons from leaving the app (except a hard reset initiated by holding both Home and Power).
Source: Hands-on: Securing iOS, pwning your kids with Apple Configurator 1.2