1) Can you add experiences and edit your personal essay after you've submitted your app?
2) Are letters of eval the only thing you can add after verification?
1) No.
2) You can add a new MCAT date, LORs, or schools/programs you want to have receive your application, or change your name, DOB, gender, personal contact information, ID #.
From page 72 of the AMCAS Instruction Manual:
"Thoroughly review your application prior to submitting. After you submit your application, you can only make changes to the following sections:
ID Numbers,
Name, including Full Legal Name, Preferred Name, and Alternate Names,
Contact Information including Permanent and Preferred Mailing Addresses,
Alternate Contact Information,
Date of Birth, Birth Address, and Sex,
Letters of Evaluation (only additions of up to 10 letter entries and notifying AMCAS of a letter no longer being sent),
Next MCAT testing date,
Add Medical Schools and change existing Program type (deadlines, fees, and restrictions apply), and
Release application information to your pre-health advisor."
