Q: Change iCloud password

You can reset your password by going here: https://iforgot.apple.com/iForgot/iForgot.html.  After doing so, to change the iCloud password on your iPad, go to Settings>iCloud, tap Delete Account, then sign back in with the new password.  This deletes the account and your synced data from your iPad but not from iCloud.  Provided you are signing back into the same account, your data will be synced back to your iPad when you sign back in.

Before deleting the account, save your photo stream photos to your camera roll (if not already there) by tapping Edit, tap the photos, tap Share, tap Save to Camera Roll.