Where can I view a list with all messages and their status?
Please go to Menu → Messages. This is especially useful for users on the Basic and Premium plans, for which a tap is required to send a reminder. You can start your morning off by going to Menu → Messages, where you'll find a list of all messages that need to be sent everyday, including Today, and tap 'Send now' on each of them.
From the upper right corner you are able to filter the messages and select which messages you would like to see: Upcoming/Sent/Failed/Delivered.