Hello al0007,
Thanks for using Apple Support Communities.
I see you have some questions concerning security on your iPad with iCloud Keychain. First of all if your iPad has iOS 9 installed, you make it more difficult for someone to gain access to it by increasing the passcode to either 6 characters or an alphanumeric passcode:
To change your passcode or passcode settings, go to Settings > Touch ID & Passcode. On devices without Touch ID, go to Settings > Passcode.
You'll find several settings and options:
- Turn Passcode Off.
- Change your passcode. Enter a new, six-digit passcode. Or tap Passcode Options to switch to a four-digit numeric code, a custom numeric code, or a custom alphanumeric code.
- Require Passcode—Immediately: By default, as soon as you lock your screen, you'll need to enter your passcode to unlock it. If you don't want to need your passcode immediately, change this setting.
- Allow Access When Locked: Allow access to some features when your device is locked, including Notifications View, Siri, and Control Center.
- Erase Data: Choose whether to erase your device automatically after ten failed passcode attempts.
Use a passcode with your iPhone, iPad, or iPod touch - Apple Support
Use these passcode settings to maximize passcode security:
- Set Require Passcode to Immediately.
- Disable Simple Passcode to use longer, alphanumeric passcodes.
- Enable Erase Data to automatically erase the device after ten failed passcode attempts.
iOS: Understanding data protection - Apple Support
However if you want to totally eliminate any chance of someone having access to your iCloud Keychain, then simply disable that option in your iCloud settings.
iCloud: Change iCloud feature settings
Cheers.