How to edit the Portfolio Items Category/Archive Template and Sidebar Settings

Hello,
I’m looking for instructions on how to edit the category/archive templates for Portfolio Items.

When I create categories for Portfolio Items, those category pages are automatically generated. They include “Archive:” in the title and the sidebar appears to be a default with Pages, Categories, and Archive for Posts (not Portfolio Items).

I’m confused as to why a custom post type already in the theme doesn’t have it’s own set of controls for single posts, category pages, etc. (if there is an area to control all this, I cannot find it).

I attempted to use the Blog Layout settings to specify a specific page, then adjust the layout settings on that page to use a custom widget, but that doesn’t affect the categories/archive template for Portfolio Items. I used a Portfolio Grid on that page (which, oddly, has no controls for column/row padding). How does one control the spacing in between the entries?

If there is a clear area to customize the Portfolio Items category/archive pages (adjust title, layout, sidebar settings, etc.), please provide instructions. IF NOT, would you consider providing controls in Theme Options for this custom post type (just like the Blog)?

I changed the sidebar settings to have a specific widget area for “Archives”, but that only affects the blog, and not the Portfolio Items category/archive pages.

Any assistance/guidance would be greatly appreciated.