1. Can I send an encrypted note to other people? If so, how do I do that?
    Yes, you can send an encrypted message to other people with android phones by SMS. Assume you have a locked note and want to send it to Alice. First, you open the note, but do NOT enter the password. Then choose the menu item "Send Note", and pick Alice from the contact list. Alice's email addresses and mobile phone numbers are displayed to allow you pick one to send the note to. Just select a mobile phone number, and press the "Send" button. Then the encrypted note is sent to Alice's phone through SMS. 
    Once Alice receives the SMS on her Android phone, she can import the message into the Android notes application and read it if she knows the corresponding password. Of course, you need to figure out a way to share the password with Alice (for example, giving her a call to tell her the password).

  2. Is there any way to recover a locked note if I forget the password?
    No. A locked note is encrypted with its password. Without the password, you cannot recover the contents of the note. You can still delete the note though to clean up your note list.

  3. What program can I use to open the backup files on the SD card on my PC?
    The backup files are sqlite database files. If you want a text file containing your notes, you can use the "Export" menu item. 

  4. Why does the check list feature not work sometimes?
    The check list mode is enabled only when the phone is in portraits mode. While the phone is held in landscape position, a check list note is in the edit mode. This way, users can switch between the display mode and the edit mode quickly by changing the position of phone.