The first part of Kapp details are
If the space is set to a single page app for its display page, you will not receive an option for display page in the kapp.
Setting the kapp to Display Page allows you to set the jsps used for the various pages for the kapp.
Setting the kapp to redirect URL allows you to set the URL you wish the kapp to redirect to when it is accessed.
The Attributes tab is where any kapp level attributes are set. Note that attributes are defined here (Kapp Attribute Definitions), but the values in each attribute are set in this tab.
The attributes defined here are generally things that will be used in workflow and/or the theme/bundle and are used across all kapps. Things such as:
Also here are fallback attributes for forms, in case attributes are not defined at that levels, such as:
Kapp fields are special fields for the kapp that will allow you to search across forms. These fields are the only way to search across various forms via field values. For example, you can search for all form submissions requested by (content of "Requested By" field) a specific user, but you could not search for all forms with a specific user id in a field called "Contact" because "Contact" is not a kapp field.
It is not required that forms within the kapp contain the kapp fields, but they are a very powerful tool.
The Security section for the kapp contains 4 kapp settings and 4 default settings for forms within that kapp.
Form Display controls who can see (and therefore submit) the form. It is not possible at this level to allow someone access to see but not submit the form. That would need to be controlled with rules on the front-end, such as an advance condition, or within the workflow engine after submit (to not process or delete the submission).
Form Modification controls who can change/update the form. This is often set to a security definition that includes form developers and platform admins.
Submission Display controls who can see submissions. This is often set to the submitter of the submission and platform admins. Submission Display access also becomes important when retrieving search results. Searches will error if they contain too many (>25) submissions the user cannot access. This is something to keep in mind when determining access for various forms and when constructing search queries.
Submission Modification controls who can modify a particular submission. This is often set to the submitter of the submission and platform admins.