A: Soon!

• Strengthens the global password used to encrypt all Notes and attachments to these Notes. The App generates your global password from your App password and PIN, and it is this global password that protects the individual unique passwords that are randomly generated for every Note and for every attachment/Media item attached to your Notes. If you do not assign a PIN, then only your App password protects the passwords to all your non-padlocked Notes and their attachments. Often the App password is stored in your KeyChain, but the PIN you choose isn't stored anywhere.
• Enables your app to lock if unused for a specified time period when left running in the background. (Otherwise, if app is left open in the background, anyone who grabs your unlocked phone can access your Notes.)

• Pros: Usability: You can unlock your app simply by unlocking your phone.
• Cons: Security: If your Keychain (device password) is compromised, people will have access to your Notes (unless you have the PIN).
(You can always Padlock your most sensitive Notes for additional protection.)

• If you don't, then a copy of each attachment will remain in the Media Library unencrypted (so you are really only padlocking the Note text itself in that case). If you do, the encrypted copy of the attached content will exist only in the Note (accessible only from the Note after opening the secure Nandemo App and entering the padlock password for the Note). Please note: The Media Library we are referring to in this topic is the Media Library of this App itself -- not Apple's Photo/Media Library. So, this question refers to an image (picture), video, or audio clip you have taken from within this app (and therefore exists only in this App's Media Library). If you brought in a picture or video from outside this App, you would have to delete it yourself on the outside to make the image encrypted in the Note the only available copy.