I'm starting a business that helps small businesses build and maintain a website. I will be managing most aspects of the website, including domain names and email addresses. I like the idea of setting my clients up with Google Apps Standard Edition so that all I have to do is point the MX records to their servers. I guess I have a few questions about this:
Google actually has a reseller program that you might be interested in: http://www.google.com/apps/intl/en/business/resellers/index.html I don't know if you can officially "resell" the standard edition since it's free, but I bet you can get answers to all your questions on that website even if you don't sign up for that program.
This may not be the type of automation your after but standard edition does provide ways to bulk create users and offers API's and desktop utilities for migration from existing mail providers. I personally have not used these features but you can access them from the "Advanced Tools" tab when logged in as an administrator.