I’d like to be able to see all the newly added cards first when viewing the store.

I’d like the option to turn my wedding occasions into anniversary reminders after that date

As the copyright belongs to the artist, which shows that you care about your artists and is a great thing to promote, I think the wording on the reverse should reflect that – something like:
© “Artist’s name”, designed exclusively for Wuzci/produced by Wuzci

Also, I think you should push the fact that the company cares about the environment. Your website says “We use recycled paper to create our cards and envelopes, print with non-toxic inks, deliver with minimal emissions and even plant trees as part of our Green Tree Promise.” Why not shout about this on the backs of the cards, too?

The ability to choose the message or design on the inside of the card.

Demographics would be great to have to we could tailor our cards , i.e. women in their 30s from West Yorkshire, and numbers of subscribers currently signed up to Wuzci

An overview of which genres of cards sold that month would be fantastic too, i.e. –% of people wanted kids birthday cards, and this –% ordered good luck cards etc

A monthly breakdown of my card sales, which ones were sold and how many of each would be grand.

I’d like to be able to upload my designs, set the title, description and categories; just like it would on Etsy.

I’d really like to be able to change the card I have selected, when I find an alternative card more suitable for the person or occasion 🙂

As the card collection grows it’s becoming harder to filter for the exact cards I’m looking for. It’d be great to have things like Age, Gender, Relationship, Style etc.