1) Will this delete the db2 user associated with the schema?
no, I am pretty sure you have to revoke the grants at the database level.
2) Will all the tables and content associated with the schema be deleted
3) If I am running this with a user that has admin permissions on the DB where the schema exists is that sufficient, or does this need to be a sysadmin db user? Or just granted dropin.
Run with a who has execute on the procedure and drop authority on the objects. I would just run with someone who has admin permissions.