Adding additional fields to panels
Yes. You can do that with Fieldable Panels Panes (FPP). Here is a quote about it (from the module's project page):

... creates an entity that may be used in panel panes to create fieldable entity panes. These panes can be created either directly in the Panels UI or in a separate administrative UI and later added.
Once added, they can appear in the &quot;Add content&quot; dialog to be easily reused. Since they are fieldable entities, they can contain any kind of data that field API can provide.
Each entity supports revisions, and any revision can be made current without having to make a new revision.
Access control is provided by the CTools access method, for both view and edit access.
Bundles are supported and can be added via the UI or hook_entity_info_alter().
A Trello board is being used to help coordinate development.