How many ipod touch back-ups can I have ready if needed? How do I get iTunes to save additional back-ups?

The only way I know is, after yoa make a backup, move the backup to another location. Keep doing that since iTunes only maintains one backup in the backup location for each device. Each subsequent backup just modifies the previous backup with the changes.

Where are iTunes backups stored on your computer

The folder where your backup data is stored depends on the computer's operating system. Make sure the backup folder is included in your data-backup routine. iTunes places the backup files in the following places:

• Mac: ~/Library/Application Support/MobileSync/Backup/
  The "~" represents your Home folder. If you don't see Library in your home folder, hold Option and click the Go menu.
• Windows XP: \Documents and Settings\(username)\Application Data\Apple Computer\MobileSync\Backup\
  To quickly access the Application Data folder, click Start, and choose Run. Type %appdata% and click OK.
• Windows Vista, Windows 7, and Windows 8: \Users\(username)\AppData\Roaming\Apple Computer\MobileSync\Backup\
  To quickly access the AppData folder, click Start. In the search bar, type %appdata% and press Return.

Yes, you need to move them back to where they cam from. When yo do they al should be listed in iTunes>Preferences>Devices. When you restore from backup you should be offered which one to restore from if there is more than one listed.