questions about Features and Groups

Trying to understand how groups and features work.

Regarding groups, I take it that they are sets of features that will be displayed together but I see no way of adding features to a group. How would this be accomplished?

If my assumption is correct and there is a way to add features to a group, can the same feature be added to several groups? I have different types of products which would have some but not all features in common. I features may be assigned to multiple groups will the complicate importing feature values in any way?

Regarding “feature code” in both group and feature edit, is its significance purely internal to CS-Cart? Will it be ever be used by an admin and if so, to do what? I want to use a rational assignment of feature codes but since I don't know what they are for I can't.

Thanks in advance for any insights.

Duh. Groups are of categories or products and allow affiliates to target them with banners. But in marketing I don't see any affiliates item. I guess this is an add on this would need to be activated.