setting up a system like you are asking about would require quire quite a bit of hand coding to accomplish and is not supported.
it is possible to make the coupon code and amount data base driven, but making the discount name database driven is the tough part.
See the following thread for details on setting up database driven coupon codes.
showthread.php?t=21482
as far as creating the database tables, that would need to be done manually, eCart wont create the tables for a coupon code system for you.