Custom fields field settings

Aloha! Is there any documentation on the Field Settings portion of creating a Custom Field. Specifically, how do the different Field Types work, i.e., Checkboxes, radio buttons, SQL. And for field types like Checkboxes, how do the Values and Default Values interact and work. It looks extremely powerful for some of the items that our current system stores or processes.

Thank you,
Ben Sevier
NMRA