Currently, we only have CMS page type properties which we can edit and change few settings but for Ecommerce page types we don't have any such mechanism in Admin Mode. It would be very helpful if Episerver can provide this feature.
Due to how Catalog content is defined, I don't think this can be done in any reasonable way. You can technically use Commerce Manager to make changes to metaclass (Add/remove metafields), but the recommendation is to use the strongly typed content type
Episerver provides CatalogContentBase to manage commerce related functionality and IContent for the CMS (Pages, Bolcks etc..) .So I think this is not required.
Correction: There is no ICatalogContent. Catalog content extends CatalogContentBase which inherits ContentData which itself implements IContentData (which inherits IContent).