there is a limit to the size a cookie can be, maybe the form is beyond that size limit.
the exact size limit changes from browser to browser. see this page for details on the IE limits:
as for the second button, theres no real trick to it, just go to Insert -> Forms -> Button to add another button, set the type to submit and the name to something like "saveIt"
for the server behaviors on the page, like validation or Insert, set the trigger to use the standard submit button being pressed so they don't trigger when the save it button is pressed.