Hi,
I'm rather new aswell to the ASA but maybe this will help in some way:
After a "write memory" command "show startup-config" should display the same as "show running-config". As I can understand it does not in Your case.
If You do a "show bootvar" do You have a "CONFIG_FILE" set?
If so maybe you should take a look at this:
http://www.cisco.com/en/US/docs/security/asa/asa80/command/reference/b.html#wp1352110
Look for "boot config"
My "CONFIG_FILE" is not set, and as I can understand it should not be in a default config.
Hope this helps in som way..