1. I would like to modify the TIMESTAMP, changing it from UTC to EST
2. Removing Deadline from the body of the email
You can modify the notification templates via Advanced Vault Settings to remove the deadline, instructions in the user guide: https://www.m-files.com/user-guide/latest/eng/personalizing_notification_messages.html#personalizing_notification_messages
I'm not sure about the timestamps but they may be using the regional settings from the server's system account so you could check that the system account is in the correct location. Instructions in the bottom half of this support article ("Copy your current settings to: -> Welcome screen and system accounts"): https://m-files.force.com/s/article/How-to-manage-date-and-number-formats-in-M-Files