We create custom diecuts and sell them from our existing site, is it possible for us to have an inventory Item where the user supplies a string of text, type and size of font, and color selection during the add to cart operation. We also need to update the online store as we create new stock diecuts, is this possible?

Yes. We have fully customizable products, where you can add any type of attribute to a product you like. You can add your own product images for these products. This feature is also great for custom albums and cards.