Hi silent11,
I've been doing eCommerce since 1995 and have mainly used a programme called Interchange. It has a very wide user base, therefore well supported, mature, feature rich, secure and has in-built support for many popular payment gateways. Its strengths come in ease of use via a mechanisim called IML (Interchange Markup Language), but embedded Perl and/or ASP like syntax can also be used. It supports SQL Dbs or flatfile and with a little Perl knowledge you can be up-and-running in a short space of time. Almost all the features you asked about are available with the exception of storing the Credit Card numbers, that is severely frowned upon. I don't mean to cause any flame bait but that is the number one NO-NO! in eCommerce, don't store CC numbers, just don't do it...

There is mailing list support which is amongst the most useful I have ever subscribed to and after a steep learning curve you can have a shop that is capable of almost anything at your fingertips.

No point in reinventing the wheel, and certainly no need to roll your own, almost all the pitfalls have been encountered and fixed with this package. Its also written in Perl.